Exam 2 Landforms and Landscapes

Mass Wasting

downslope movement of earth material due to force of gravity. Water can play a role

Vector

Symbolizes a variable that has magnitude (length) and direction (angle)

normal force

normal to slope that acts perpendicular into the slope; Wcos

shear force

acting parallel to slope; Wsin

Strength

resistance to stress

Shear strength

resistance to shear stress

effective normal stress

rock (mass wasting)

detaching as solid rock that generates few lines and deposits large chunks of rock

soil (mass wasting)

relatively thin layer of unconsolidated fine grain feature

Earth (mass wasting)

many feet thick layer of unconsolidated fine grain feature

Debris (mass wasting)

Very poorly sorted, dry with at least 20% of gravel

Mud (mass wasting)

Saturated fine-grained sediments, mostly consists of silt and clay

Slow mass wasting

You cannot see this type of mass wasting overtime, but you can see some cumulative effects

Stem Flow

water flows down a plant’s stem or trunk which delays delivery of water to the surface

Throughflow

Water from rain seeps through the surface and flows through the ground

Return Flow

Water that has seeped into the ground by throughflow, flows back out on the surface

Base Flow

Groundwater seeps out into a stream

Sheetwash

Unchannelized flow

Stream

Channelized flow

Ephemeral Flow

Water is temporary that only flows before or after a rainstorm or snowmelt. Typically, in arid climates however there can be very small channel examples in any climate.

Intermittent Flow

Water flow is seasonal typically during the wet season or semiarid or wet dry climates.

Perennial Flow

Water all year regardless of rain as it is fed by groundwater.

Rills

first channels to form, tiny, inches deep/inches wide, ephemeral flow

Gullies

next size up from rills, few feet wide, few feet deep, ephemeral flow in any climate

First-Order Channels

Channels that are perennial flows but no perennial tributaries, fed mostly by gullies, however it is groundwater fed to stay active all year

Tributaries

Contributes its flow to a larger stream

Stream System

Connected network of tributaries

Stream Order

Channel’s position in system hierarchy with higher orders being larger channels with lower elevation

Drainage Basin

Region drained by a given stream system

Drainage Area

Size of drainage basin (mi²,km²)

Drainage Divide

Boundary around drainage basin that has some kind of high ground

Base Level

Lowest position the stream flows to

Ultimate Base Level

sea level

Regional base level

topographic low more inland basin typically arid climates

Temporary base level

consists of resistant rock along the stream that holds water

Exterior drainage

Stream system reaches the ocean

Interior drainage

Stream system ends at a regional base level

Rating Curve

empirical relationship between gage height (or pressure in intake pipe) versus discharge at a gaging station.

Manning Equation

Used to find velocity necessary for reconstructing past discharge from flow evidence

competence

max. size clast the stream can carry at its present velocity.

Capacity

Max. amount of load the stream can carry at its present velocity

Corrosion

fluvial erosion process that is chemical erosion by removing ions

Hydraulic action

fluvial erosion process that force of water alone breaks and removes clasts quarrying loose material and erosion of bedrock.

Abrasion

fluvial erosion process where water with load is used as tools to break off more rock matter then it can form water twirls that make potholes

Attrition

fluvial erosion process that has abrasion of clastic particles in transmit as the size of load decreases and shape of bedloads round downstream

Cavitation

fluvial erosion process where it is erosion by bubble collapse. Flow velocity increases into a constriction, lowers pressure which gas bubbles form, velocity then decreases exiting constriction, and pressure increases, gas bubbles collapse, breaking the rock

Delta

fluvial deposit where a stream enters a standing body of water

delta plain

the fluvial part above the water in a delta

prodelta

the subaqueous part of a delta

Birds foot delta

a type of delta characterized by numerous, long, isolated channels that branch outward from a river's mouth

cuspate delta

a triangular or tooth-shaped delta formed where a river mouth meets a straight shoreline, shaped by strong waves that push sediments outwards, creating a pointed, symmetrical shape

arcuate

a type of river delta characterized by a smooth, semi-circular, outward bulge, formed where river sediment is deposited in a balanced environment with moderate wave and tidal action

tide dominated

commonly large sediment dispersal systems controlled both by high-energy coastal processes and high-discharge rivers

solifluction

slow moving of soil on permafrost

talus

slope of broken rocks

scree

rocks of comprising a talus slope

Thalweg

Streamflows thread to max vel