absorption capacity - The rate at which a spreading facility transmits water to the subsurface, commonly in units of gallons per square foot.
accomodation - With reference to the coastal stratigraphic regime - the space available for sediment accumulation
acre-foot - The volume of a mass of water one foot thick over one acre, amounting to 43,560 cubic feet or 325,828.8 gallons.
adjudication - With reference to California water law, a determination either by a civil action, an action of the State Water Rights Board, or a combination thereof, by which proportional rights among legally permissible users is determined.
aerobic decomposition - Decomposition of organic substances by bacteria which uses oxygen in the process; also, aerobic digestion.
aggradation - With reference to the coastal stratigraphic regime - the building up of stream deposits so as to maintain a uniform grade.
Airy wave theory - A theory of fluid dynamics which approximates the propagation of gravity waves on a fluid surface such as that of the ocean (also "linear wave theory") with sufficient accuracy to be useful for many engineering purposes.
Anacapa fault - A fault indicated by its offshore trace in Santa Monica Bay that is either a splay or the main trace of a fault zone that includes the Malibu Coast fault and extends from near Raymond Hill in Pasadena to beyond Santa Cruz Island, a distance of over 110 miles.
anaerobic decomposition - A two-stage process involving, first, acid fermentation in which fecal matter and other easily decomposable materials are converted to organic acids, nitrogen compounds, and carbon dioxide, followed by another alkaline fermentation, also referred to as methane fermentation, during which the organic acids and nitrogen compounds are decomposed into ammonia compounds, carbonates, and methane (Imhoff, 1989, pp. 211- 213); also, anaerobic digestion.
ancestral - With reference to the science of geomorphology, a term of art referring to a remnant landform produced by a set of forces, commonly a combination of tectonism and erosion, that is no longer active.
angle of internal friction - The angle between the normal and shear force vectors when shear failure occurs.
appropriated water - Water taken from its natural location such as a stream or a ground-water basin for use in some "distant land," i.e., beyond the boundaries of its natural occurrence.
appropriation doctrine- With reference to California water law, one of two basic doctrines establishing the means by which the use of water may be acquired characterized by its aquisition in one place and transport for public use in another (see riparian doctrine).
appropriative right - With reference to California water law, a principle of first in time, first in right, which is predicated on the usefulness of water over its non-use, first applied to situations where placer miners took water from streams through the use of flumes or ditches for mining uses in non-riparian lands
aquifer - A formation or the section of a formation from which ground water can be produced economically. For example, a formation from which ground water could be produced at a rate of, say, 5 gallons per minute would be sufficient to supply perhaps two or three residences could be regarded as an aquifer. However, if the demand was for a greater production rate, say for a factory or some sort of extensive agricultural development, it would not be regarded as an aquifer.
art - The application of fundamental principles and skill for the creation of some object.
attitudes - The position of a planar surface in space expressed in terms of a strike component and a dip component.
avalanche - With reference to landsliding, a slope failure involving the sudden movement of a section of a steep rock slope that more or less either involving a more or less loose mass of debris in a slope or a section of slope that with movement downslope becomes a largely fragmental mass. Also see fall.
axially symmetrical - With reference to Cartesian coordinates, descriptive of curves such as those of the sine and cosine functions in which, as x increases, y takes on values that are the product of a function of x and a constant that ranges between +a and -a.
ba - Abbreviation for "before the present time."
back-shore - The area of a beach landward of the fore-shore reached by waves only during periods of especially high surf commonly combined with high tides and surge, conditions in Malibu so infrequent, on the order of tens or years or more, that characteristic low-lying vegetation has developed.
bank storage - A term of art implying that the permeable section through which a stream is flowing has reached saturation, a condition resulting from the influent character of the stream or ground water recharge from adjacent areas, or both.
barrier bar - A sand bar formed along a shore landward of which is a lowland wherein water commonly is impounded sop as to be either partially or completely isolated from the adjacent shore waters.
Basin Plan - The basic plan adopted by each of the nine California Regional Water Quality Control Boards outlining that board's operational scheme.
beach - The area consisting of a fore-shore and a back-shore, extending form a line taken for legal purposes in Malibu as the mean high tide line, to a line defined by either the base of a relatively steep slope that may be natural or artificial and occasionally directly attacked by waves.
bedding plane - A surface formed because of a break in a depositional sequence during the formation of a mass of sedimentary rock. The tendency of some beds to separate along bedding planes commonly is the result the deposition of finer-grained materials such as silt or clay during at the end of a depositional sequence which inhibits cementation or otherwise develops as a relatively weak zone.
back-calculation - A method selecting design shear strength values based on the assumption of a safety factor of unity at the time of failure in instances where the topography at the time of failure is known.
bedrock - A term of art referring, generally, to well indurated and cohesive earth materials and commonly applied to geologic formations.
bent - With reference to construction, a member of a system of a horizontal framework transverse to a longitudinal structure such as a pier or a bridge.
biota - The animal and plant life of a particular locality, i.e., it's flora and fauna.
bp - With reference to geologic time, an abbreviation meaning before the present.
break - With reference to water waves, the collapse of the wave crest due to the steepness of the wave front resulting in a transition from the kinetic energy of orbital movement to the kinetic energy of flow.
breaker - A mass of water in the process of translating from a water waves to a translationing water masses due to the instability of wave height; two kinds are recognized: spilling breakers in which the translation occurs gradually from the wave crest downward over the advancing wall of the wave, and plunging breakers in which the wave amplitude becomes suddenly so steep that most of the fails as an wall of water arcuate in the direction of propagation and sectionally somewhat tubular or tunnel-like.
bulkhead - As used in beach-front construction, a wall commonly of timber or concrete used to support drain field material and protect it from wave erosion.
butte - A hill or ridge bounded by one or more steep slopes.
canyon - A relatively large and deep channel such as a chasm or a gorge with relatively high and steep sides, and most commonly formed by stream erosion.
causeway- An elevated roadway over and open and relatively extensive expanse of water supported by columns.
celerity - With reference to wave theory, the velocity of waves within a wave group which is twice that of the group itself; also, "phase velocity."
cell - In biology, an individual encapsulated organism which lives and serves as a fundamental entity in higher forms of life.
civil works - Projects related to the earth the design of which requires civil engineering expertise and involves the support and placement of structures such as roads, dams, drainage control structures, and buildings.
claptosis - The reflection of waves from a bulkhead.
cnoid - One or more mathematically derived functions that describe periodic surface gravity waves that are lengthy relative to depth and as length approaches infinity become a solitary wave.
coefficient of friction- A dimensionless constant characteristic of two materials acting in shear and by experiment determined as the ratio of shear and normal forces acting on that surface at the time shearing starts, called the coefficient of starting friction, or during shearing, called the coefficient of sliding friction; also calculated as the tangent of the angle of internal friction.
coagulation - a process of adding chemicals such as salts of aluminum or iron to reduce the repulsion between hydrophobic colloids causing them to attract and form flocs.
coastal marine lagoon - An area adjacent to a body marine water which periodically and with reasonable regularity develops a brackish condition due to normal exchanges of marine and terrestrial waters such that it supports an ecology that has developed over a period of years that is special to such conditions.
cobbles - rock grains in the range of 64 mm to 256 mm in longest dimension (Pettijohn, 1975, p. 30, Table 3-3).
coefficient of friction - A dimensionless constant characteristic of two materials acting in shear and by experiment determined as the ratio of shear and normal forces acting on that surface at the time shearing starts, called the coefficient of starting friction, or during shearing, called the coefficient of sliding friction; also calculated as the tangent of the angle of internal friction.
cohesive strength - Resistance to deformation independent of the direction applied force; also cohesion.
competent - In lithologic terms, describing relatively strong rocks or rocks relatively more resistant to erosion.
contact - With reference to the geologic formation, a surface due either to deposition, faulting, or physiochemical alternation, where two formations meet.
controlled conditions - With reference to artificial fill, fill placed under conditions required the geotechnical engineer of record and generally as specified in the local building code.
contour drain - A pipe perforated by specific design in its upper half and laid nearly parallel to slope contours and at a depth as near the base of an upper zone of soil or other relatively weak surficial material as is practical for the purpose of intercepting ground water and directing it off-site as controlled surface flow.
correlative right- With regard to ground water, the equal right of all landowners in an enclosed basin to the ground water underlying their properties subject to its reasonable and beneficial use, and, in the case of an adjudication, a proportional use thereof.
crest - With reference to waves, the highest point on a wave surface above the mean level datum; also the entire surface above the datum; as with the wave trough, the vertical distance from the highest point on the crest to the datum is the wave amplitude. The sum of the amplitudes above and below the datum is the wave height.
crystal - A solid consisting of one or more specific arrangements of atoms giving rise to six specific classes of forms.
critical surface - In the field of geotechnical engineering having the lowest shear strength based on the configuration of the surface and its estimated shear strength.
cut-and-fill - A process that develops along streams that deposit entrained loads as a result of varying rates of flow. The deposited load of an earlier freshest fills the channel and forces the succeeding freshet to overflow the channel thereby cutting a new one. Also, the structure showing a cut channel profile and an overlying generally coarser-grained fill. mass.
cytoplasm - The gel-like fluid if a cell containing the organelles.
Darcy's law - The rate at which water of a given temperature passes through the interstices of a granular medium is equal to the product of the cross-sectional area of the medium though which the water passes, the hydraulic gradient, and a constant characteristic of the medium referred to as the hydraulic conductivity.
decay - With reference to the transmission of water waves in deep water, the increase in wave-crest length and decrease in amplitude both due primarily to their arcuate transmission mission which in terms of oceanic distances have a point source; with reference to the transmission individual waves within groups, the diminution of wave amplitude the individual waves within the group ostensibly due to frictional heat.
deep-seated failure - A term of art describing a shear landslide at any depth that is commonly involves bedrock and is used to distinguish landslides such as flows, avalanches, or rockfalls all of which are directly related to configuration of the slope surface.
dendritic - A pattern of stream branches similar to those of a tree in which smaller ones have confluence with larger ones generally at acute angles, with all eventually leading to a first-order, or "master" stream.
design storm - A rain storm that occurs in a certain way the characteristics of which are chosen as a means to implement some rain model. The design storm to implement the Los Angeles County Department of Public Works modified rational method model to calculate maximum runoff is one that occurs over a period of fours days with the most rain falling on the fourth day.
dip- The angle of a plane from horizontal measured normal to strike of that surface.
disinfection - A term of art referring to the elimination of pathogens, particularly in water. Methods include oxidation through the use of chemicals, ultra-violet light radiation, or ozonation. The most common chemical is used either chlorine gas, which in water produces the oxidized hypochlorite ions, and other chlorine compounds capable of disrupting the cellular or genetic structures of micro-organisms, rendering them either incapable of reproduction or altering cell structure - in effect, killing them. UV radiation alters the micro-organism's gene structure rendering them incapable of reproduction. Ozonation involves the manufacture of ozone which, like chlorine, is an oxidizer.
dispersal system - From AB885 DEIR, November, 2008: "... a leach field, seepage pit, mound, at-grade, subsurface drip field, evapotranspiration and infiltration bed, or other type of system for final wastewater treatment and subsurface discharge.
diurnal - With reference to water bodies, a single daily tide variation.
drain field - An excavation 4 to 5 feet in depth containing one or more perforated pipes laid in a bed of gravel for the purposes of receiving and spreading into the underlying earth effluent from a septic tank; in the form of an elongated trench some times referred to as a leach line.
drawdown - The distance between the static ground-water and the pumping level at any specific section in an aquifer.
earthquake - A transfer of potential energy to kinetic energy in the earth's interior producing seismic waves sensible to humans, and generally thought to mostly be due to movement along a fault.
earthquake focus - The location in the subsurface where an earthquake originates.
earthquake magnitude - A measure of the energy produced during an earthquake, the most common of which are the Richter magnitude and the moment magnitude.
effective stress - The reduced stress caused by the load of earth material on a surface calculated at the product of the coefficient of friction and the difference between the normal stress and a neutral stress.
effluent (noun) - With reference to water treatment, generally, the fluid emission of a treatment process; in terms of septic systems, the treated liquid, largely water, which is produced from the septic tank after anaerobic decomposition; with reference to streamflow, a condition in which the surface water of the stream is receiving ground water from adjacent areas; c.f.., influent.
effluent (adjective) - With reference to streamflow, a condition in which the surface water of the stream is receiving ground water from adjacent areas; c.f.., influent.
elastic - The property of a material such that when deformed under stress, it returns to its initial form when the stress is removed.
embayment - An indentation in a shoreline of any size.
enclosed basin - With reference to ground water, a surface depression such as a valley or a dell without a subsurface channel outlet and containing permeable granular material such as alluvium underneath which is relative impermeable bedrock, all present in such a manner that ground water in the alluvium is hydraulically sufficiently independent from any in the underlying bedrock that it can be considered separate from it in terms of its availability and legal significance.
engineering geology report - Report created by an engineering geologist that investigates and provides geologic and geotechnical recommendations, analysis, and design associated with human development.
entropic - Descriptive of the principle of entropy - the physical law that energized systems tend to return to a condition of equilibrium.
ephemeral stream - A stream that flows only during runoff such as that from rain or only for limited periods thereafter and therefore not constantly.
epicenter - The point on the earth's surface directly above the earthquake focus.
equilibrium level - Wither reference to a water surface, the position in space of a water surface over which the tidal and gravitational forces are equal.
erosion - Processes, particularly that of flowing water, but also including wind and water waves that wear away the earth's crust.
estuary - A partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea.
ESHA - Environmentally sensitive habitat area so designated because it supports species officially considered to be endangered.
ET processes - The processes by which vegetation takes water from the subsurface though the roots and plant body to be transferred to the leaf surfaces by transpiration, and then to the atmosphere by evaporation.
ET - Evapotranspiration - the loss of water from plants to the atmosphere through the metabolic processes of vegetation growth.
eukaryotic - In biology, referring to a cell with a nucleus, and structures that have specific purposes, and generally, are much more complex than and larger than prokaryotic cells and hence, more advanced.
expediter - The expediter is a person familiar with procedural aspects of property development according to the planning, building and safety, and health requirements of a particular jurisdiction. There is no state licensing for expediters although certain agencies may prefer working those who are most familiar the agency requirements and protocols.
fall - With reference to landsliding, a type of failure involving blocks of rock breaking away directly airborne or simply starting to roll or slide from steep slopes or cliffs; where a large mass of debris is involved, the term avalanche us applied.
fate - With reference aqueous constituents, their movement and either their persistence or change in physiochemical character.
fault - A fault is a surface where two masses of earth material have rub against one another thus having undergone shear movement. Since a fault is a surface, it is two-dimensional and therefore incorporeal. The characteristic movement in shear serves to distinguish a fault from a fissure. See also, fault contact and fault trace.
fault contact - A place observable on the ground where two rock masses have rubbed against one another.
fault trace - A line on a geologic map representing the intersection of a fault surface with the ground surface or with some buried surface. A buried intersection commonly is indicated as a dotted line. Where exposed at the ground surface, the trace is indicated as a relatively thick or "heavy" line to distinguish it from a thinner line representing the surface contact of two formations.
feasible - Possible with favorable results generally of an economic nature.
fetch - A term of art used to describe the area of a water body, particularly the oceans, within which wind transfers to energy to the water so as to result in water waves and defined variously as greatest length of that area in the direction of the wind, or the size of the area, or the distance of the weather shore to the point where the formation of the wind waves commences (Wiegel, 1953)..
50-year storm - A rain storm based on the statistical occurrence of recorded rain depths over a period of a year indicating, for a given region, the probability of 2 percent that a storm producing such rain depths will in any year.
fissure - A more or less tabular three-dimensional incorporeal volume formed when two masses of earth material move away from each other essentially normal to its trend, in other words, a ground crack.
fjord - A lengthy estuary resulting from a glacially eroded channel flooded by the sea; also fiord.
500-year flood - A flood that statistically has a probability of 0.002 (0.2 percent) in any year.
Flandrian transgression - A name applied to the total rise in sea level that began about 18,000 or 19,000 years ago as a result of regression of the Wisconsin glacial epoch and is in progress at the present time; during this period, episodes of especially warm periods as well as cooler periods possibly accompanied by minor glacial advance. Authorities postulate sea level from 70 to 150 meters below that at the present time when the Wisconsin glacial advance ceased.
flocculation - the agglomeration of flocs into chain-like masses formed by the addition of polymer for the purpose of inducing settling as a means to clarify turbid waters
flow - With reference to landsliding, a type of failure where a mass moves downslope as the result of a loss of shear strength more or less throughout that mass.
focus - The point or zone within the earth from which an earthquake emanates.
force - A push or a pull.
fore-shore - The area of a beach seaward of the back-shore periodically inundated due to tidal fluctuations and more or less constantly subjected to periods of wave erosion or deposition by waves and commonly affected by long-shore currents generated by the angular approach of waves.
formation - A mass of earth material which has a set of lithologic characteristics and therefore is mappable.
formation contact - A surface separating two masses of earth material with reasonably identifiable different lithologic characteristics .
fresh-water head - In sea-water intrusion calculations, the distance of the equipotential surface at a particular point above sea level.
frequency - With reference to water-wave theory, the number of waves passing a fixed point in unit time; reciprocal of the wave period.
friable - As applied to rocks, easily broken or crumbled by hand .
frictional strength - Resistance to shear movement the magnitude of which is the product of a force applied normal to the surface of shearing and a pure number called the coefficient of friction which is characteristic of that surface.
geologic hazard - A condition of the earth which, either in itself or in relation to some artificial condition, represents the potential of a life-endangerment or injury, or has the potential for significant economic damage.
geologist's log - A record of the type of materials, including ground water, encountered in a boring or trench together with thickness, depths, and comments regarding special features of such materials relevant to the purpose of the boring.
geology - The study of the history of the earth, especially shown in its rocks.
geomorph - A landform definable on the basis of its topography
geomorphic province - A relatively large area of the earth that can be characterized as having a dominant geomorphic character such as a mountain range, a valley, or a desert.
geomorphology - The scientific study of landforms and the processes that shape them.
geotechnical engineer - See soils engineer.
geotechnical investigation- An investigation to determine the engineering characteristics of a site, commonly required by local agencies as one conditions for the issuance of a building or a grading permit.
geotechnical report - One or more reports commonly including and engineering geology report and geotechnical engineering report.
geotechnical engineering report - Report using principles of soil mechanics and rock mechanics to investigate subsurface conditions and materials and determine the relevant physical/mechanical and chemical properties of these materials.
Ghijben-Herzberg phenomenon - The formation of an interface between saline and fresh ground water due to sea-water intrusion, the depth of which at a particular point is a function of the fresh-water head above sea-level at that point.
Ghijben-Herzberg principle - The formation of a zone, also referred to as an "interface," that develops when sea water intrudes a coastal aquifer in which the freshwater head is higher than sea level. This zone separates the denser sea water from the overlying "fresh" water of the aquifer. This condition is maintained due to the aquifer interstices which by friction reduce the rate of diffusion that otherwise would occur.
Goat Buttes - A name given to three of four incised meander necks along Malibu Creek some 2 to 5 miles upstream from the its confluence with Cold Creek.
goop - A term of art invented for present purposes to mean plastic icky stuff that sticks to surfaces; think of grease or dirty, rotten lard.
gorge - A term of art meaning a relatively large, deep, and narrow canyon with very steep sides.
grading - Artificial movement of earth material commonly according to a specific plan for the purpose of changing the topographic configuration of a site either by adding or removing such material.
groin - A wall some material such as rock, sheet metal, or timbers constructed essentially normal to a shore for the purpose of obstructing of longshore flow in order to cause deposition of earth materials carried in the flow.
ground water - Water in the earth's subsurface, and particularly that near the surface which moves in response to gravity and the principles of hydraulics.
ground-water basin - A determined mass of alluvium or bedrock within which ground water collects as in the case of valley fill, and which, arguably, there is no outflow through a surface or well defined and known subsurface channel such as to deem the ground water as tributary.
group velocity - With reference to water waves, the rate of movement in distance per unit time of a group of waves, i.e., the rate at which the wave energy is transmitted; the group velocity in water so deep that the energized water does not reach the bottom; this velocity is half that of the celerity, or phase velocity, i.e., the velocity of waves within the group.
gulch - A term of art meaning a steep-sided channel, commonly one due to local stream erosion, less deep and extensive than a ravine.
Holocene - An epoch of Quaternary Period generally considered to have begun 10,000 years ago and still in progress.
hydraulic conductivity - A characteristic of a permeable material measuring the rate of flow of a fluid through a given cross-sectional area of that material as a function the physical characteristics of the material and the hydraulic gradient in this country with regard to water originally having the dimensions of gallons per day per square foot, but now rationalized and probably universally accepted as having the dimensions of velocity.
hydraulic gradient - The change in fluid energy per unit mass (also referred to as head), per unit distance, above a datum.
hydraulics - The study of the manner in which water or other fluids are used to create force.
hydrologic equilibrium equation - A method of calculating the volumetric change of water within a given volume of the earth and overlying atmosphere in a specified period based on the fact that within that volume for any period the sum of the total inflows and losses in storage must equal the total sum of total outflows and increases in storage; also "hydrologic balance" and "hydrologic budget."
hydrogeology - The study waters in the earth.
hydrogeomorphic - A term of art relating conditions resulting from water acting in specific ways to create certain kinds of landforms.
hydrology - The study of the surface waters of the earth.
hydrophilic - In water chemistry, descriptive of a substance to which water is attracted.
hydrophobic - In water chemistry, descriptive of a substance which is repulsed by water.
impact force - The force resulting from a change in momentum due to impact calculated as the ratio of the change in momentum to the period during which the change occurs.
intercept cohesion - A stress due to cohesive strength of a material derived from a Cartesian plot of normal shear strength on the abscissa plotted versus shear strength on the ordinate where the failure envelope intersects the ordinate.
infinite slope analysis - A mathematical model which determines the safety factor of a section of soil or other surficial earth material on a slope of constant gradient and infinite longitudinal extent.
influent - A condition indicating the loss of surface water to the subsurface; with reference to streamflow, a condition in which the surface water of the stream is passing as ground water into the materials through which the stream is flowing; c.f., effluent.
instream flow -A recently developed environmental term meaning the amount of water needed in a stream to adequately provide for downstream uses occurring within the stream channel; such uses cover some or all of the following other than that for human drinking water: aquatic habitat, recreation, wetlands, navigation, hydropower, riparian vegetation, and water quality, including waste assimilation. (Wikipedia - Google)
intermittent stream - A stream that flows much of the year but seasonally ceases to flow.
interstices - Openings in granular or fractured materials which, if connected, allow for the passage of fluids.
Kentucky crossing - A stream ford sufficiently free of boulders or deep, loose, fine-grained deposits that would prevent wagons or other vehicles from crossing during periods of sufficiently low water. Also referred to as an "Oklahoma crossing" or an "Arizona crossing."
knob - a relatively small, commonly rounded, isolated hill.
lagoon - A term of art indicating a relatively small coastal embayment which experiences at varying intervals tidal flows from an adjacent relatively large water body
laminar flow - Fluid flow in which masses move in parallel layers and hence along and hence along essentially parallel paths; also : non-turbulent flow..
landslide - A relatively rapid downward and outward movement of a mass of earth material in response to gravity.
landslide debris - Any earth material that has moved as a result of landsliding.
lateral corrasion - The natural tendency of streams in areas of low gradient to develop a sinuous channel by erosion and deposition after the stream reaches grade.
leach line - See drain field.
licensure - A legal status conferred by a legislature, county, or city, to perform certain tasks for profit in order to assure the application of a certain degree of knowledge and skill for the protection of the public.
limit equilibrium analysis - An analysis of slope stability that predicts the occurrence of a landslide along a postulated surface of shear when the gravitational force of a mass acting along that surface reaches the limit of the shear strength can be mobilized along that surface; the phrase "limit equilibrium" refers to the fact that in accordance with the second law of motion, the driving and resisting forces are equal until the limit of the resisting forces is reached.
liquefaction - The temporary condition in which saturated granular sediments become, in effect, liquid as the result of ground shaking that separates grain contacts thus eliminating the shear strength of the mass.
lithology - The study of the physical characteristics of rocks.
lithosphere - Broadly, the solid part of the earth as distinct from the hydrosphere or the atmosphere, but also used to describe only the earth's outermost zone, the crust, which lies above the earth's mantle.
littoral - The zone along a shore in which materials are move in currents along the shore response to the energy of waves.
littoral current - A net transport of water in the littoral zone resulting from a preferred angle of wave approach to the shore and the kinetic energy of the water caused by the breaking wave.
littoral drift - Fragmental materials commonly of sand size, but up to the size of boulders, transported along the shore by the littoral current.
magma - A molten, and hence essentially liquid, mass of materials which at lower temperature, or pressure, or both, would form rock.
Malibu Canyon - Arbitrarily, for present purposes: the canyon downstream from the confluence of Malibu Creek and Cold Creek as shown in 1981 photorevision of the U.S. Geological Survey 7.5-minute Malibu Beach quadrangle. Note: the desirability of this definition arises from the fact that in the absence of any such designation "Malibu canyon," the downstream reach of Malibu Creek herein designated would be considered as flowing in Triunfo Canyon.
Malibu Creek floodplain - Arbitrarily for present purposes: the area of deposition by Malibu Creek from the point where the creek is crossed by Cross Creek Road just west of its intersection the intersection of that road with Mariposa de Oro in the Serra Retreat area.
marine terrace - A relatively narrow surface of very low relief formed along a shore by gradually advancing wave erosion and commonly recognized by a shoreline angle at the base of a sea cliff in which there are beach deposits of coarse-grained littoral drift grading seaward into marine bottom sands over the terrace surface. Older such features are found at elevations above sea level due either to lowering of sea level, or coastal land uplift, or a combination of both and, thus free of coastal erosion processes, have become covered with colluvium or terrestrial stream deposits. Combinations of stream deposits, colluviums, littoral drift, and marine bottom sands all no longer subject to wave erosion are referred to as marine terrace deposits. Marine terraces in the process of formation along many shores lack terrace deposits other than those of littoral drift and marine bottom sands, because such masses of colluvium and stream deposits that collect at the shoreline angle are reduced by wave erosion and become littoral drift.
marine terrace deposits - see marine terrace.
mean high tide line - Theoretically, the line of defined by where the edge of sea meets the land as a result of the tide level calculated as the average of the annual higher high tides that occur during the year, as determined from a local reference elevation.
meander - A circuitous channel section which, through a progressive process of lateral corrasion and deposition, forms a semi-circular loop, a series of which is called "scrolls" by some authorities and has an average width sometime called a meander belt (see illustration). Note: "spur," although not a commonly used term, apparently is derived from the U- or spur-shaped end of the neck. Commonly, as the series progresses downstream, the neck becomes so narrow that it is breached, thus isolating a reach of the stream that then forms an oxbow lake. See illustration
mineral - A naturally occurring inorganic substance that can be expressed by a chemical formula and is characterized by one or more crystal habits.
Miocene - An epoch of the Tertiary Period generally considered to have occurred from 23.8 to 5.8 millions years ago.
microplate - A term of art applied to relatively small a section of the earth's crust which appears to be an isolated fragment of a parent tectonic plate.
Mohr-Coulomb model - A criterion for describing the shear strength of earth materials consisting of the sum of a cohesive strength component and a frictional strength component.
modified rational method - A model for calculating rain runoff developed for Los Angeles County which modifies the rational method based on a design storm and takes into account variations in runoff due to characteristics rates of infiltration of different surfaces and related bulk flow.
moment magnitude - A alternative definition of earthquake magnitude based on ______.
msl - mean sea level.
mudflow - A flow landslide having debris composed mostly of finer-grained materials such as sand, silt, and clay, and having a relatively high water content rendering it especially fluid.
neutral stress - The stress resulting from the difference between the normal stress due to a particular mass and a buoyant force acting on that mass or an hydraulic uplift force applied to the essentially impermeable base of that mass.
Newmark analysis - Newmark analysis estimates the cumulative permanent displacement to be expected of a block on a slope when there is applied to it a seismically induced critical acceleration. An excellent explanation of the Newmark analytical method is given by Jibson et al., (1998).
nomenclature - A systematic set of terms describing similar objects, concepts, or conditions.
normal stress - The ratio of a force of a mass applied normally to a surface and the area of that surface, where the force is calculated as the product of the volume and the unit weight of that mass - in soil mechanics understood to be the drained unit weight.
100-year flood - A flood that statistically has a probability of 0.01 (one percent) in any year.
open ocean wave regime - Transmission of energy in relatively deer ocean waters characterized by propagating sinuous surface waves of common length and amplitude in which there is a constant exchange of potential and kinetic energy with respect to an equilibrium sea level.
organelle - A specialized structure or "subunit" within a cell that has a specific function.
organic carbon - carbon which occurs as a chemical compound such as carbon dioxide and the many organic compounds
orogeny - An episode of major crustal movement during which mountains are raised and including deformation and faulting as well as peripheral deposits of or both shallow- and deep-water sediments, intrusion and metamorphism at depth, volcanism, and earthquakes.
orographic phenomenon - The increase in rainfall resulting from a water vapor-laden air mass being lifted as it passes over mountainous terrain, thus decreasing in temperature and causing the water vapor to condense as rain in progressively greater amounts at higher and colder elevations.
osmosis - A process in which water molecules pass naturally through a semi-permeable membrane to an aqueous solution with a relatively low concentration of water molecules according to the principle of diffusion. Diffusion occurs independently of the presence of dissolved solids in the receiving solution even though it has a higher concentration of dissolved solids. Prevention of passage in the reverse direction of some ionic species in the receiving solution is prevented because the membrane repels their charge, of uncharged molecules because of their size, and, apparently, of others simply because the flow is in the opposite direction. This diffusion continues to occur until pressure on the receiving side of the membrane is great enough to prevent normal diffusion. The process of reverse osmosis involves creating artificially an osmotic pressure the forces water molecules in the opposite direction through the membrane thus developing an aqueous solution relatively free of constituents other than water molecules.
osmotic pressure - the hydrostatic pressure exerted by a solution of relatively high ionic concentration necessary to prevent osmosis into that solution when it is separated by a semi-permeable membrane from a solution of relatively low ionic concentration.
overlying landowner - With reference to California water law, one by virtue of owning land in an enclosed basin has a right to withdraw ground water collected there.
oxbow - A term derived from the shape of an ox horn used to described a characteristically curved lake or pond which results from a meander becoming isolated by lateral stream erosion.
P waves - One of two body waves generated during an earthquake which is faster than the other, the S wave, and vibrates as a compressional wave parallel to the direction of its propagation. One of two body waves generated during an earthquake which is faster than the other, the S wave, and vibrates parallel to the direction of its propagation.
pebbles - rock grains in the range of 4 mm to 64 mm in longest dimension (Pettijohn, 1975, p.30,Table 3-3).
peneplain - a surface of low relief caused by wide-spread sub-aerial erosion to a local base level.
perched ground water - A saturated body of ground water isolated above the regional saturated zone.
perennial stream - A stream that flows all year.
permeable - capable of transmitting fluids.
permeability - In hydrogeologic terms, the general condition of being able to transmit fluids to be distinguished from hydraulic conductivity
phase velocity - With reference to the movement of water waves, the rate of distance per unit time of the individual wave; cf. group velocity.
phototroph - An organism that manufactures its own food from inorganic substances using light for energy; all green plants, certain algae, and some bacteria are phototrophs.
phreatic - Refers to ground water subject to extraction by wells
piping - The development of pipe-like tubes in relatively fairly compact surficial materials such a soil or colluvium as a result of ground water exiting the mass as a spring. Such spring flow erodes the materials as a result of its increased velocity. The erosion increases the area of spring and the resulting increased flow increases the erosion. In fairly compact materials, and especially those with a clay binder, caving does not occur; rather, the erosion causes a tube to be formed which works headward. Such tubes can develop lengths in the tens of feet or perhaps more under the right conditions. Pronounced: pipe - ing.
plate tectonics - The study that recognizes the outermost shell of the earth to be composed of relatively thin but essentially discrete masses forming from the extrusion of basaltic magma along cracks at the surface and spreading laterally resulting in three types of plate boundaries: "divergent" along the cracks where two plates form, "convergent" where two plates collide, and "transform" where two plates rub against one another.
platform - In geomorphology, a broad more or less level surface, generally the kind formed by wave erosion. c.f. marine terrace.
Pleistocene - An epoch of the Quaternary Period generally considered to have an occurred from 1.8 million to 10,000 years ago.
Pleistocene orogeny - An ill-defined episode of crustal deformation an uplift which is thought by some to have begun about a million years ago after a period of about a million years during which there was crustal quiescence and terrain was extensively eroded and reduced to areas of low relief.
Pliocene - An epoch of Tertiary Period generally considered to have occurred from 5.8 to 1.8 million years ago.
plunging breaker - As applied to water waves, a wave in which its advancing front has become so steep as to form a cylindrical configurationthat fails in the dramatic, waterfall-like mode.
political correctness - the idea that concern for the emotions of others takes precedent over truth, especially regarding political decisions in order to pander to those who are essentially emotionally driven and whose ability to think critically is statistically extremely rare, i.e., the electorate.
pre-historic - A time prior to any written or photographic record; as commonly used in geologic analysis, it refers only to a locality to be inferred from the context of the discussion.
pressure - Force per unit area exerted in a fluid and hence equal is all directions.
progradation - With reference to the coastal stratigraphic regime nomenclature - seaward advance of a shoreline due to deposition of sediments deposited by a stream. Occurs as a result of sea-level rise and high sediment flux. This is the case of the shoreline at the mouth of Malibu Creek - there the sea level rise is due to the Flandrian Transgression and the high sediment flux due to periodic flooding of the creek.
progradational parasequence set - With reference to the coastal stratigraphic regime nomenclature - parasequence set in which successively younger parasequences are deposited farther seaward (basinward); overall the rate of deposition ion is greater than the rate of accomodation. Consequently, a single boring cannot demonstrate this condition.
progressive wave - With reference to hydrodynamics, the advancing form of the water surface similar in shape to a sine curve indicating advancing movement of energy through the water rather movement of the water itself which is limited to oscillation as the energy passes.
prokaryotic - In biology, referring to a cell lacking a nucleus and internal structures of the complex eukaryotic cells and hence less advanced
pseudostatic analysis - A method of determining a landslide seismic safety factor by assigning seismic coefficient that increases the driving force of a slope mass along an existing or postulated surface of landslide failure.
public use - With reference to California water law, any beneficial use including the storage and sale of water to public or private entities deemed advantageous to the general economy. (Hutchins, p. 152)
Quaternary - The name given to the geologic period from 180 million ago to the present within which are recognized the Pleistocene and the Holocene epochs.
rational method - A model for calculating rain runoff based on the equation, Q=CIA, in which Q is the runoff rate, C is a variable related to the surface, I is the rainfall intensity, and A is the area receiving the rain.
ravine - A term of art meaning a steep-sided channel, commonly one due to stream erosion, less deep and extensive than a canyon but deeper and more extensive than a gulch.
recharge - Addition of ground water to an aquifer.
recurrence interval - The statistical period between a simple defined event such as a true statesman being elected to political in the USA, or the period between an event having some magnitude such as when more than 20 percent. of the electorate actually votes. Also, the return period. Less facetiously, for rainfall, based on the record, period expected between the occurrence of a selected rainfall depth or greater. In equation form:
T = (n+1)/m - where T is the recurrence interval, n is the number of event, and m is the rank of the event in question where "rank" is the place of the event in a list of the total events ranked from largest to smallest. The reciprocal of the recurrence interval of an event is the probability of that event occurring.
regime - With reference to hydrology, a particular aspect of a stream regimen with regard to its rate of flow.
regimen - With reference to hydrology, the characteristic behavior of a stream, i.e., for present purposes, the collection of regimes a stream may exhibit.
regional saturated zone - An extensive zone of ground water above some relatively impermeable zone of bedrock rendered so by its inherent lithology, or the degree of lithologic pressure.
regression - With reference to the coastal stratigraphic regime - advance of the shoreline seaward due to due to stream deposition (in the case of Malibu Creek, stream deposition is due to rise of the SM Mountain block since the mid-Pleistocene - EDM). Normal regression occurs in the presence of a stable or rising base level. Forced regression occurs in the presence of a decreasing base level. A regressing sea results in progradational stacking patterns.
rejuvenation - With reference to hydrology, a lengthy period during which the previous flow rate of a stream has been substantially increased.
retrogration - With reference to the coastal stratigraphic regime - movement of a shoreline landward due to transgression
ria coast - A coast characterized by lengthy mountain-sided estuaries which are subaerially eroded canyons or valleys flooded by the sea.
riparian - A term specifying something related to a stream such as vegetation that occurs only along its course, or a legal right associated with the ownership of land adjacent to a stream; sometime applying to a contained water body such as a lake.
rip-rap - A mass of rock, commonly loose angular clasts of cobbles or boulder size, placed on a slope to protect it from erosion.
riparian doctrine - With reference to California water law, one of two basic doctrines establishing the means by which the use of water may be acquired characterized by its appurtenant relation to the land through which water flows (see riparian right - With reference to California water law, a principle of real property usufructuary in character, whether for mining, irrigating, power generating or any other beneficial use, predicated on the ownership of land adjacent to a stream rather than ownership or possession of the stream course itself.
riparian right - With reference to California water law, a principle of real property usufructuary in character, whether for mining, irrigating, power generating or any other beneficial use, predicated on the ownership of land adjacent to a stream rather than ownership or possession of the stream course itself.
ripples - With regard to water- wave formation, small waves on the order of an inch or so in length commonly as observed by agitating water in a pond.
risk - The probability, expressed either mathematically or in general terms, of an adverse occurrence. With reference to earthquakes, the probability of the occurrence of a geologic hazard (Reiter, 1990, p. 3).
RHSMI - Abbreviation for: Raymond Hill - San Miguel Island referring to a zone roughly several thousand feet in width between these Raymond Hill near the City of Pasadena on the east and the westernmost of the channel islands off Santa Barbara on the west, a distance of over 110 miles.
Richter magnitude - One of several scales indicating energy released in terms of a mathematical interpretation of the amplitude of the first earthquake shock as recorded on a special seismograph, originally designed for the southern California area, commonly referred to as "local magnitude," and now less used than the moment-magnitude scale.
rock - A relatively rigid aggregate of one or more minerals.
rock avalanche - A type of landslide involving the sudden movement of a section of a steep rock slope that more or less immediately becomes a largely fragmental mass.
rock fall - A type of landslide involving one or more blocks of rock commonly of cobble to boulder size breaking away directly from a cliff or other steep surface and rolling, sliding, or bounding downslope with occasional air-borne trajectory; where a large mass of debris is involved, the term avalanche is applied.
Rossi-Forel scale - An early arbitrary scale of earthquake intensity based on damage and effects on human perception.
reach - A particular section of a stream.
reverse osmosis - See osmosis.
S waves - One of two body waves generated during an earthquake which is slower than the other, the P wave, and vibrates as a shear wave normal to the direction of its propagation.
safety factor - In terms of shear landsliding, the ratio of forces or stresses tending to resist movement in shear to the forces or stresses tending to cause such movement.
safe yield - The volume a ground-water basin is estimated to yield annually based on records indicating the mean annual recharge.
saltation - In the subject of stream hydraulics, the movement of fragments in response to stream flow along the stream bottom by essentially bouncing
scarp - A section of earth surface formed by some particular geologic process such as faulting or erosion having a relatively high gradient on either side of which are earth surfaces of relatively low gradients.
sedimentary rocks - Rocks made up of individual grains deposited in a fluid, commonly water and commonly with rigidity derived from some sort of natural chemical compound such as iron oxide or calcium carbonate which acts as a cement.
seepage pit - A cylindrical hole, commonly 25 - 30 feet deep and 5 - 6 feet in diameter feet used for the purpose of receiving and spreading septic-tank effluent into the underlying earth. Pits must have a dome-shaped cover set a prescribed distance below the surface and fitted with an access port; they may be lined or filled with gravel and, in the latter instance, fitted with a standpipe to allow for pumping.
seiche - An individual wave of oscillation, also referred to as a "standing wave" in an partially or entirely enclosed water body that continues, pendulum fashion, after the cessation of the originating force. which may have been either seismic or atmospheric (U.S. Army Corps of Engineers); alternatively, progressing waves which appear to oscillate because they are reflected from bounding surfaces (EDM)..
seiching - The process of seiche wave movement.
seismic event - Any occurrence the source of which induces seismic waves, particularly the earthquake but also including certain artificial activities as explosions or the movement of heavy equipment.
seismic hazard - A seismic event which "... has the potential for dangerous earthquake-related natural phenomena such as ground shaking, fault rupture, or liquefaction ... (that) could result in adverse consequences to society..." (Reiter, 1990, p. 3)
seismic safety factor - The safety factor against shear landsliding under dynamic conditions due to the passage of seismic waves.
seismicity - The degree of shaking to which an area of the ground is subject due to an earthquake of other source of energy generation.
seismic waves - Earth motions of various kinds, most notably shear waves and compressional waves, by which mechanical energy is transmitted through the earth.
semi-diurnal - With reference to water bodies, tide variations occurring twice daily.
septic system - A facility for the disposal of waste water, particularly sewage, consisting of a septic tank and some sort of spreading facility.
septic tank - A fabricated tank commonly of concrete or plastic which receives waste water, particularly sewage, for the purpose of, first, storing it while the material decomposes under anaerobic conditions and, and second, passing the effluent to a spreading facility.
shear - With reference to mechanics, a differential application of parallel forces acting in opposite directions; also a type of landslide occurring due to shear failure.
shear - With reference to landsliding, a type of landslide which fails because of a loss of strength along a more or less discrete basal surface.
shear landslide - A landslide that fails by shearing along one or more discrete surfaces; where such surfaces are approximately planar, such slides are referred to as "translational," and where curvilinear they are referrede to as "slumps."
shearing - Movement caused by the application of shear stress.
shear - With reference to landsliding, a type of landslide which fails because of a loss of shear strength along a more or less discrete basal surface.
shear strength - Resistance to deformation by shearing commonly defined in earth materials as the sum of a cohesive strength and a frictional strength, c.f. Mohr-Coulomb model.
shear stress - Force per unit area due to the application of a shear.
shear surface - A two-dimensional and therefore incorporeal location between two masses acting on each other in shear.
shoal - A term of art when used as a noun to an area that is commonly exposed at lower tide levels, and when used as an adjective to describe a particular area where ocean water is shallow; the gerund form, "shoaling" means increasingly shallow.
shoreline angle - The line formed by the intersection of a marine terrace with an adjacent sea cliff.
shoreline regression - the seaward advance of the shoreline due to a drop in sea level commonly accompanied by a retrograding facies shift, i.e., a stacking of continental deposits over marine deposits.
shoreline transgression - the landward advance of the shoreline due to a rise in sea level commonly accompanied by a transgressing facies shift, i.e., a stacking of marine deposits over continental deposits.
silt - In mechanical terms, mineral granular materials with textures in the range of 0.004 - 0.062 mm.
sine function - A trigonometric function which relates on acute angle of a right triangle to the ratio of the length of the side opposite that angle to the length of the hypotenuse; a plot Cartesion plot of this function commonly is used to infer the cross-sectional configuration of the surface of a water wave.
slough - Also "slew." With reference to hydrology, a term of art used to describe either a low marshy condition or a low-energy channel passing through a marsh. It is pronounced sloo or slew, in contrast to sluf, which has an entirely different meaning.
soil - A generally loose or slightly consolidated mass of inorganic materials formed at the earth's surface by the physical and chemical decomposition of rocks and also commonly containing organic material.
soils engineer - In California, a civil engineer specializing in the testing of earth materials and using such the results of such test data in the design of structures; now generally synonymous with "geotechnical engineer.".
soil gas - Gas that permeates the interstices of soils and rocks and is in equilibrium with air of the atmosphere.
spilling breaker - As applied to water waves, a gradual breaking of the wave crest that in theory begins to occur when the angle of the surface on either side of the crest reaches 120 degrees. As the process proceeds, the water involved in the breaking "spills" down the advancing foreslope of the wave. Because of the appearance of the longitudinal foam of a spilling wave, the process of such wave formation is sometimes referred to as "feathering."
splay - As commonly used, a fault that is a branch of a more extensive fault.
spreading - With reference to ground-water recharge, the introduction of water to the subsurface.
spreading facility - With reference to the septic system, an back-filled excavation such as a drain field or a leach line, or seepage pit either back-filled or open, any combination thereof, used to introduce effluent from the septic tank to the subsurface, but see dispersal system; with reference to ground-water recharge, any low-lying area commonly with berms for containment and situated so that introduced water percolates in the subsurface as aquifer recharge..
stakeholders - Interested third parties who participate in public reviews concerning proposed governmental projects, particularly those with special environmental aspects.
standing wave - With reference to hydrodynamics, the result of the reflection of progressive waves from the bulkhead of an enclosed basin with the progressive waves such that their interference appears to make the surface simply oscillate.
static safety factor - The safety factor of a slope against shear landsliding under static conditions.
storm surge - A local rise in sea level elevation along a shore due to the force of high-velocity offshore winds acting on the sea surface.
strain - The change of a dimension of a mass under an applied stress expressed as a ratio of such a change to that in the unstressed state.
strength - The capability to resist deformation.
stress - A component of force acting in a particular direction on a unit area of a surface; c.f., pressure.
stresses - Plural of stress.
stress regime - A condition in which sequential applications of stress in which principal stresses are more or less constant.
strike - The direction of a horizontal line on a surface such as a fault or a bedding plane.
strong-motion recorder - One of a number of kinds of instruments sensing accelerations of 0.01 - 0.02 gravities, i.e., 0.32 - 0.64 feet per second per second commonly sensible to humans as a force in excess of normal human weight. For example a 150-pound man, just sitting there minding his own business would feel a push about 1.5 to 3.0 pounds under a suddenly applied seismic acceleration of such magnitude although, arguably, a woman I know setting there talking on the phone wouldn't feel a damn thing.
structure - A lithologic term referring to features of a rock mass other than texture such massiveness, bedding, and fracturing.
structural fill - Earth material placed according to well defined standards as to mass configuration, graded sizes, degree of compaction, and method of construction, generally to achieve a certain level of shear strength and serve either for the support of structures or to buttress slopes.
style - With reference to faults, the character of its attitude and offset.
Subdivision Map Act - A California state law originally enacted in 1915 to clarify title to subdivided land, but which since by various amendments is used to insure proper design of tracts or other subdivisions of land.
subduction - In plate tectonics, a type of convergent boundary in which one plate is forced beneath another.
superposed meander - A stream meander originally established on a surface of low relief, which has maintained its course by eroding vertically in response to uplift of that surface; see also tectonic processes - Various processes having to do with deformation of the earth's crust, and in particular through usage, "mountain building."
superposed stream - A stream the drainage pattern of which originated in equilibrium with its native terrain that has retained that pattern upon incising into an underlying terrain of "foreign structures" in the sense used by Johnson (1932, p. 92) to mean one in which, under normal circumstances, would have resulted in a different drainage pattern.
superposition - see superposed stream.
surge - With reference to shore processes, the advance of water as a wave on to the land to an elevation higher than mean sea level in response to either wave or storm dynamics, but without significant breaking.
suspension - With reference to stream hydraulics, the movement of finer-grained materials entirely carried by the water
swell - The ordered distribution of discrete ocean water waves that emerges from a fetch.
tectonic plates - discrete and essentially rigid slab-like surficial sections of the lithosphere about 10 miles thick in ocean basins and as much as 125 miles thick in some continents, that move over the more or less plastic asthenosphere (look it up, too).
tectonism - Various processes having to do with deformation of the earth's crust, and in particular through usage, "mountain building."
teletsunami - A recently coined terms to describe a tsunami capable of traveling with recognizable effects at a point a great distance, on the order of thousands of miles, from its source.
tensional strength - Resistance to deformation of a mass subjected to forces applied to it acting in opposite directions.
Tertiary - The name given to the geologic period between 3.6 and 65.5 million years ago, within which are recognized the Paleocene, Eocene, Oligocene epochs (or Paleogene Period), and Miocene and Pliocene epochs (or Neogene Period) .
Terzaghi effective stress model - A modification by Karl Terzaghi, the "father of soil mechanics," of the Mohr-Coulomb model of shear strength. "Effective stress" refers to the reduction in normal stress due to the presence of a saturated section which Terzaghi thought was due to water pressure acting on some theoretical "wavy surface," but is now known to be due, generally, to buoyancy.
terrace - A step-like feature of the earth's surface analogous to a stair consisting of a scarp that is either vertical or has a relatively steep gradient analogous to a step riser and a surface that is either horizontal or has a relatively low gradient analogous to a step tread.
texture - A lithologic term referring to the size and shape of grains of rocks.
thalweg - The line connecting the lowest points along the bed of a stream generally depicted as a line on a map or a stream cross-section.
tidal bore - A wall of water advancing up a stream channel or an increasingly restricted coastal inlet caused by a rising tide.
tide wave - A deformation of a water surface such as that of the ocean, due primarily to the gravitational attraction between the mass of the water and masses in space, particularly the mass of the moon, but also to some extent that of the sun; the term "tidal wave" commonly but less frequently these days used, incorrectly, to refer to a tsunami, is best left to verbal relcis of the past.
torque - Stress or strain produced by rotating or twisting an elastic material.
transcurrent - Fault movement more less parallel to the strike of the fault.
transmissitivity - The rate at which ground water of a prevailing kinematic viscosity is transmitted through a unit width of an aquifer section under unit hydraulic gradient.
transpiration - The passage of water unused in a plant through its leaves, analogous to perspiration by animals.
trace - See fault trace.
traction - With reference to stream hydraulics, movement of the coarsest materials of the stream load, generally of cobble or boulder size, along the stream bed by pushing or rolling.
trocoid - The locus of a point on a circle as the circle rolls along a straight line.
tsunami - A water wave generated in large water bodies, particularly oceans, due to a sudden change in the configuration of the bottom commonly due to earthquakes and less well documented, submarine landslides. As a result, one or more such waves can travel thousands of miles in deep open where wave lengths may be 100 miles or more and wave velocities of hundreds of miles per hour. Depending on coastal configurations, the uprush of broken waves can travel several miles inland. It is reported that the tsunami received its name from Japanese fisherman who, on returning home from the sea, have noticed extensive wave damage to harbor facilities. The enclosed and gradually narrowing width of some harbors would help to increase the heights of waves approaching the shore. In the Japanese language, "tsu" means harbor and "nami" means wave or water wave. Literally translated, tsunami means "harbor wave."
unit weight - The weight of a mass per unit volume of that mass.
uprush - A term of art used to describe the advance of water on to a shore when a wave "breaks," i.e., when its energy, which prior to breaking was half potential and half kinetic, becomes essentially entirely kinetic. It is the onshore advance of uprush and its aftermath that causes most damage from a tsunami. Furthermore, it is the retreat of uprush water from a shore under normal surf conditions that cause the potentially hazardous rip currents (erroneously "rip tides" and "undertow"); c.f., surge.
unconformity - A surface of erosion or non-deposition separating older from younger rocks; implicit in this definition is a hiatus, i.e., a significant break in the temporal record.
undercut slope - A slope in which bedding planes are exposed that have dips in the same direction as the slope that are less than the slope angle.
USGS - United States Geological Survey
usufructuary - Pertaining to a usufruct, a right to use the property of another.
vadose zone - The permeable zone of the subsurface through which ground water passes under the force due to gravity.
valley - A term of art meaning a relatively large elongate depression with relatively high but not necessarily steep side slopes. Most commonly, valleys are associated with, if not entirely formed by, stream erosion, and therefore they have stream outlets.
vulcanism - A term applied to volcanic activity.
water depth - With reference to water waves, the distance between the bottom and the mean water elevation at static equilibrium.
watershed - A common term indicating the area of slopes with gradients to stream tributaries leading to a single master stream, based on the idea that one such slopes surface runoff will, unless diverted to the subsurface or the atmosphere, eventually reach that stream. Ground water in a watershed becomes part of the runoff only if it reaches the surface within the watershed.
wave amplitude - In elastic wave theory, the maximum perpendicular distance of the wave from its axis of symmetry; with regard to water waves, wave height is twice the amplitude.
wave crest - With reference to water waves, the section of the wave surface above the water equilibrium level.
wave length - With reference to water waves, the distance between any two similar points of single wave configuration, e.g., between adjacent crests.
wave period - With reference to waters, the time for a single wave to pass a fixed point in space; the reciprocal of the wave frequency.
wave surge - With reference to waves meeting the shore, a flow, i.e., an advance over the land of water during which there is a transition of wave energy to flow energy with accompanied, if at all, by only a partial breaking of the wave - a condition common to steeper shores; c.f. uprush.. .
wave trough - With reference to water waves, the section of the wave surface below the water equilibrium level.
west-oblique transcurrent - Descriptive of movement along a west-trending fault such that the area on the northern side of the fault moves both upward and westward with respect to the areas on the southern side of the fault.
whaler - With reference to pier construction, a horizontal timber beam either floating or tied structurally to pier pilings to assist in temporary boat landing activities such as loading and passenger boarding.
wildcat - In the oil industry, applied primarily to an exploration drilling operation in an unproven area.
Wisconsin - The latest glacial cycle of the Pleistocene Epoch generally considererd to have lasted from about 95,000 years ago to 19,000 years ago.
work - The product of a force and the distance though which it acts.
zone - With reference to faulting, an area of the earth's surface within which fault attitudes and traces are roughly parallel so as to suggest crustal response to a single stress regime.
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