part 1

paleontologist

______________ speciallize in the study of fossils

saltation

a series of short leaps or bounces off the bottom

gradient

the downhil slope of the streams bed

headwater

usually a stream's gradient is greatest at its ___________

streams

what are one of the most effective sculptors of the land

valleys

what are the most common land form on the earth's surface

tectonic forces

what can cause the overturning or disruption of beds so much that the principle of superposition cannot be used

turbulance

what counteract gravity in saltation

uplift

what is a key factor in the formation of many incised meanders

urbanization

what is one cause of severe flooding

velocity

what is the key factor in a stream's ability to erode, transport and deposit

relative

_____________ time is the sequence in which events took place , rather than the number of years involved (geologist are more concerned with this number)

correlation

__________________usually means determining time equivalency of rock units (within a region, continent)

noncomformity

a _____________ is a contact in which an erosion surface on plutonic or metamorphic rock has been covered by younger sedimenary or volcanic rock (generally indicates deep or long erosion before subsequent burial)

stream

a body of running water that is confined in a channel and moves downhill under the influence of gravity

flood plain

a broad strip of land built up by sedimentation on either side of a stream channel

v-shaped

a cross section of a stream in steep mountains is usually what shape

alluvial fan

a large fan or cone shaped pile of sediment that usually forms where a stream's velocity decreases as it emerges from a narrow mountain canyon onto a flat plain

actualism

a principle that the same processes and natural laws operated in the past are those we can actually observe or infer from observations as operating in the present

divide

a ridge or strip of hight ground dividing one drainage basin from another

transporting overcoming

a river's energy is used for 2 thing ___________sediment and ___________ resistance to flow

tributary

a small stream flowing into a larger one

delta

a stream flowing through quiet waters usually builds a _________- a body of sediment deposited at the mouth of a river when the river's velocity decreases

key bed

a very distinctive layer can be used to correlate rocks over great distances (volcanic ash)

angular uncomformity

an __________________ is a contact in which younger strata overlie an erosion surface on tilted or folded layered rock (implies- deposition, lithofication, uplift, erosion)

formation

bodies of rock of considerable thickness with recognizable bodies characteristics that make each distiguishable from adjacent rock units (named after geographic features)

unconformities

contacts representing buried erosion surfaces-a surface or contact that represents a gap in the geoligic record with the rock layer above the contact being considerably younger than the rock beneath

unusual

correlation by rock type is more reliable if a very ____________sequece of rock or involved

numerical

dating based on radioactivity allows us to determine a rocks ___________ age (age given in units of time)

potholes

depressions that are eroded into the hard rock of a streambed by the abrasive action fo the sedimet load

dendritic

drainage pattern- acute angles- looks like branches of tree or nerves (formed on uniformly erodible rock)

discharge velocity

during floods a streams ___________ and ___________ increase

silt clay

flood deposits are usually ____________ and __________

reoccurance intervals

floods are described by_________________- the average time between floods of a given size

disconformity

in a ________________ the contact representing missing rock strata seperates beds that are parallell to one another (probably the older rock eroded away

uiformitarianism

james huttons concept that geologic operating at preset are the same processes that operated in the past eventually became known as teh principle of ______________ (the present is the key to the past)

natural levees

low ridges of flood-deposited sediment that form on either sid of a stream channel and thin away from the channel

lower

meandering is common in the ________________reaches of a river

traction

movement by rolling, sliding or dragging

absolute

numerical age is also known as _________age

runoff

only 15% TO 20 % of rainfall normall ends up as surface __________ in rivers

riprap

protective walls of stone or concrete constructed along river banks- particularly along curves

meanders

rivers that carry fine-granined silt and clay in suspension tend to be narrow and deep and to develop pronounced sinuous curves called _________

intrusive contact

rock which intruded after orginal rock layer was formed

dissolved load

soluble products of chemical weathering processes -ions

stream terraces

steplike landforms found above a stream and its flood plain

bar

stream deposits may take the form of a ___________- a ridge of sediment, usually sand and gravel, deposited in the middle or along banks of a stream- (formed when velocity or discharge decreases0

shape roughness

the ____________ and _________of a channel controls a streams velocity

hydraulic action

the ability of flowing water to pick up and move rock and sediment

drainage pattern

the arraingements, in a map view of a river and its tributaries

faunal succession

the discovery of william smith who realized that fossil species succeed one another through the layers in a predictable order

abrasion

the erosive process that is usually most effective on a rocky streambed is _______________

bed load

the large or heavy sediment particles tht travel on the stream bed - moved by traction or saltation

base level

the limit of downcutting: theoretical limite for erosion of the earth's surface

deposition

the low velocity on the inside of a river's curve promotes sedimnent ___________

sinking

the mississippi delta is ____________as upstream dams catch sediment, reducing the delta's supply

hydodrologic cycle

the movement and interchange of water between the sea, air and land

mouth

the place where a stream enters the sea, a lake, or a larger stream

inclusion

the principle of _______________ states that fragments included in a host rock are OLDER than the host rock

superposition

the principle of _______________ states that within a sequence of undistrubed sedimentary or volcanic rock, the layers get younger going from bottom to top

original horizantally

the principle of ____________________ states that beds of sediment deposited in water formed as horizantal or nearly horizantal layers

lateral continuity

the principle of _______________________ states that an original sedimentary layer extends laterally until it taper or thins at its edges

cross cutting relationships

the principle of ___________________________ states that a disrupted pattern is older than the cause of the dispruption

downcutting

the process of deepening a valley by erosion of the streambed

coarsest

the sediment near the river is _______________

point bar

the sediment on the inside of a curve the consists of a series of arcuate ridges of sand or gravel

suspended load

the sediment that is light enough to remain lifted indefinitely above the bottom by water turbulence

velocity

the streams ___________ is the distance water travels in the stream per unit of time (up to 15miles/hr)

stratigraphy

the subdiscipline in geography that uses interrelationships between layered rock or sediment to interpret the history of an area

contacts

the surfaces seperating 2 different rock types or rocks of different ages (used to decipher geological history)

contact metamorphosed

the tilted layers immediately adjacent to granite bodies are ____________________ a result of intrusion of hot granite magma

drainage basin

the total area drained by a stream and its tributaries

headwaters

the upper part of the stream near its source in the mountain

discharge

the volume of water that flows past a fiven point in a unit of time

fossils

these are common in sedimentary rock and their presence is important for correlation

placer

these types of deposits happen where running water has mechanically concentrated heavy sediment

sheetwash

thin layers of unchanneled water flowing downhill

trellis

this drainage pattern consists of parallel mainstreams with short tributaries meeting at right angles (forms in an area of titled layers of resistant rock)

rectangular

this drainage pattern has 90 degree angles- develops on regularly fractured rock

radial

this drainage pattern is where streams diverge outward like spoke of a wheel (forms on high conical mountains)

continental divide

this extends from the yukon to mexico and seperates drainage basin east and west

stream channel

this is where a stream normally stays- it is a long narrow depression eroded by the stream into rock or sediment

distributaries

this marks the surface of most deltas, - small shifting channels that carry water away from the main river channel and distribute it over the surface of the delta

foreset

this type of bed from the main body of the delta- they are depositied at an angle to the horizontal

topset

this type of bed is above a foreset and is nearly horizontal

bottomset

this type of bed is in from of a foreset bed - it is deposits of t he finest silts and clay

physical continuity

this type of correlation traces physically the course a rock unit

headward

this type of erosion allows a stream to lengthen its valley - it is the slow uphill growth of a valley above its orginal source through gullying - mass wasting and sheet erosion

lateral

this type of erosion is the erosion and undercutting of a streams banks and valley walals as the stream swings from side to side across its valley floor

flash

this type of flood is local, sudden with large volumes over a short duration-often triggered by heavy thunderstorms

incised

this type of meander retain their sinuous pattern as they are cut vertically downward below the level at which they orginally formed- result is no flood plain

graded

this type of stream is one that exhibits a delicate balance between its transporting capacity and the sediment load available to it

braided

this type of stream is typically shallow flows in a network of interconnecting streams

rills

tiny streams made from overland sheetwash

sediment

what might be deposited as velocity decreases

continental drift

what theory uses correlation of rock type as its proof

slot

what type of canyons are formed by downcutting

outside

when a stream goes around a curve- the region of maximum velocity is displace by inertia toward the ___________ of the curve

james hutton

who is regarded as the father of geology

charles lyell

who wrote the book Principles of Geology