Chapter 10-Streams, Rivers, and Lakes

                       Physical Geology Illustrated Vocabulary
Cochise College                                                     
Geology Home Page 
RIVERS and STREAMS
Roger Weller, geology instructor
wellerr@cochise.edu  
copyright 2018-Roger Weller
last edited: 3/21/18
  

 
flooding following fire in the Huachuca Mountains, Cochise County, Arizona

Vocabulary

alluvial fan
-is a deposit of sediment deposited at the base of a mountain where a
stream coming off the mountain dumps its load.
The sediments usually form a fan-like cone shape that gives this
structure its name.
-9 views of alluvial fans
-southern Nevada-alluvial fan-1 
-southern Nevada-alluvial fan-2 
-Yosemite-alluvial fans 
-alluvial fan-Opal's Pals

asymmetric ripple mark
-is a ripple mark structure with a steep, short slope on the downstream side of its crest
and a low angle, long slope on the upstream side. Preserved ripple marks of this type
are indicators of current directions of ancient streams.
-asymmetric ripple marks-1
-asymmetric ripple marks-2 

bar
-is a mass of sand or gravel in the bed of a stream or river.
-10 views of gravel bars
-gravel bar in Aravaipa Creek, Arizona 
-gravel bar-Opal's Pals

base level
-is the lowest level to which water can flow.
-base level-Opal's Pals

bed load
-are the materials that are being dragged along a stream as the stream flows.
-bed load-Opal's Pals

bedrock
-is the solid rock material that underlies loose surface materials.

braided stream
-consists of many parallel and interwoven streams separated by an abundance of gravel bars.
The gravel bars are deposited as the main stream slows in its flow due to loss of volume of
water and thus loses its competence and capacity.
-9 views of braided rivers

buoyancy
-Objects denser than the fluid in which they are placed will sink; objects less dense than the
luid in which they are placed will float. A dense object placed within a fluid will have its apparent
weight decreased equal to the weight of an equal volume of water that it displaces.
-density and buoyancy-Opal's Pals

channelization
-is the attempt by humans to straighten out a meandering river.

continental divide
-is a line on a map that separates the collection of drainage basins that empty into the Pacific
Ocean from those drainage basins that empty into the Atlantic Ocean.

contour line
-is a line on a map that indicates a constant elevation on the land surface.

contour plowing
-is a form of land conservation; instead of plowing in straight lines, the plowing in hilly areas follows
contour lines. The furrows left by the plow in contour plowing act as small terraces which prevent
runoff from carrying soil away.

dam
-is a structure built across a stream or river channel for the purpose of blocking the flow of water.
-10 views of dams

delta
-When a stream or river enters into a large body of water, it slows down and drops its bed and suspended
loads producing a body of land, mostly made of mud.
-map, Louisiana-Mississippi Delta 
-10 views of major deltas

dendritic drainage
-is a tree-like pattern of stream tributaries feeding a main stream or river.
-9 views of dendritic drainage
-dendritic drainage map project
-dendritic drainage pattern-Opal's Pals

deposition
-occurs when a stream slows down, loses its ability to carry sediments, and drops its load.
-stream deposition-Opal's Pals

dissolution
-is the process of dissolving a material; the material goes into solution.

dissolved load
-consists of the materials in solution that the stream or river is carrying.
-dissolved load-Opal's Pals

drainage basin
-is an area in which all rainfall is diverted into streams and rivers that feed into the same main stream or river.
-Wyoming-dendritic drainage basin
-drainage  basin-Opal's Pals

drainage divide
-is the line on a map that separates two adjacent drainage basins.
-concept of a divide
-drainage divide diagram
-drainage divide-Opal's Pals

eddy
-In stream flow an eddy is a circling or rotating patch of water.
-eddy-Opal's Pals

entrenched meander
-is the same as incised meander.
-5 views of entrenched meanders
-entrenched meander-Opal's Pals

ephemeral stream
-is a stream that only flows part of the year.  An ephemeral stream is often called a "dry wash".

erosion
-is the process of carrying away materials in contrast to weathering which causes the breakdown of materials.
-stream erosion-Opal's Pals

flash flood
-occurs when a dry wash (stream channel) that suddenly fills with water. The water level in the channel quickly
rises, surge after surge. Often the source of the water may be a rainstorm in the mountains many miles away.
flash flood- Hereford, Arizona after the Monument fire:  1  2  3  4  (black charcoal in water)

flood
-occurs when a river overflows its banks
-San Pedro River, Arizona in flood stage:  1  2

flood plain
-is the flat area next to a stream or river that consists of silt that was deposited when the stream or river
overflowed its channel during flood stage.
-Rocky Mountains Park-flood plain 

fluvial
-is an adjective that means "related to a river".

fording a river
-is the process of crossing a river and its widest and most shallow point for safety purposes; the water in the
river moves slower at this location.

gravel bar
-is a mound of gravel within a stream channel.
-gravel bar in Aravaipa Creek, Arizona-1 
-gravel bar in Aravaipa Creek, Arizona-2 
-gravel bar in stream, Oregon
-gravel bar-Opal's Pals

Great Salt Lake, Utah
-is a large lake in central Utah that has no river draining it; evaporation of water from the lake has
concentrated the salt in solution to the point where the water is saltier than seawater.
-geologic map of the Great Salt Lake 

headwaters
-are at the highest elevation of a stream channel.  It is the point where a stream just starts to form.
-headwaters-Opal's Pals

hydroelectric power
-is electrical energy created by turbines built into dams.

incised meander
-is a meandering stream that has cut downwards forming a canyon with a meandering pattern.
It is also called an entrenched meander.
-5 views of entrenched meanders
-entrenched meander-Opal's Pals

lake bed deposits
-consist of mud and silt that are dumped into a lake by streams or rivers. 
These materials settle to the bottom of a lake in nearly horizontal layers.
-lake bed deposits in Bryce Canyon-1 
-lake bed deposits in Bryce Canyon-2 

laminar flow
-describes water flowing smoothly with no turbulence.
-Aravaipa Creek, Arizona 
-Aravaipa Creek, Arizona-smooth vs. slightly turbulent flow 
-laminar flow-Opal's Pals

levee
-is a hill that runs parallel to a river and is created by multiple flooding events where the flood
waters deposit sediments as the the river overflows its banks.
-6 views of levees
-levee-Opal's Pals

local base level
-In areas where there has been relatively recent tectonic uplift and faulting, a stream may not flow
down to its ultimate base level which is sea level. Instead, the stream ends in a lake at a higher
elevation that has no outlet.

longitudinal profile
-is a graphical plot of the elevation of a stream compared to the distance from its starting point.
-stream profile-Opal's Pals

meander cutoff
-occurs when the base of a meander loop becomes so narrow that the stream erodes across it.
The cutoff meander loop becomes an abandoned meander and eventually turns into an oxbow lake.
-views of cutoff meanders
-diagram of a cutoff meander

meander loop
-is a pronounced curve or bend in a meandering river.
-meander loop diagram

meandering river
-is a river whose outline resembles a snake; the path of the river curves back and forth.
-7 views of meandering rivers
-meandering river in Rocky Mountains Park-1 
-meandering river in Rocky Mountains Park-2
-meandering river-Aravaipa Creek, Arizona 

Mississippi Delta
-is the landform consisting of mud and silt that was deposited in the Gulf of Mexico at the mouth of the
Mississippi river
-Mississippi River delta
-map-Louisiana-Mississippi Delta 

Nile Delta
-is a large body of sediment deposited where the Nile River enters into the Mediterranean Sea.
-Nile River delta

outer bank erosion
-occurs on the outside bank of a meander loop in the river.  Water travels faster on the outside of a turn,
increasing its competence and thereby causing erosion.
-cut bank erosion- 7 views
-outer bank erosion-Opal's Pals

Oxbow Lake
-is a U-shaped adjacent to a meandering river. The lake forms as a meander loop is cut off and
abandoned by the flowing river.
-8 views of oxbow lakes
-oxbow lake diagram

playa
-is a dry lake bed

point bar
-is a mound of gravel deposited on the inside river bank at a bend in the river.
-10 views of point bars
-point bar-Aravaipa Creek, Arizona
-point bar-Opal's Pals

pot hole
-is a shallow, nearly round hole worn into bedrock in a stream by abrasion from rocks being moved
by the stream.

radial drainage
-describes a feature on a map where the main drainage channels all radiate either away from or
towards a central point.
-views of radial drainage
-radial drainage pattern diagram

rapids
-consist of rapidly flowing water in a stream or river that is moving in a violent, chaotic pattern; whitewater.
-Yellowstone-rapids 
-Poudre River, Colorado-rapids 

riparian environment
-is a riverbank environment
-San Pedro River:  1  3

ripple marks
-are small parallel ridges of sand formed by flowing water or wind.
-ripple marks-1 
-ripple marks-2 
-California-ripple marks on beach 

saltation
-is a form of transportation of materials by rolling and skipping.
-saltation-Opal's Pals

sandbar
-is a ridge of sand in a stream channel.

sheetwash
-After a heavy rain, water flows as a sheet across the land, not confined to channels.
-sheetwash-Opal's Pals

solution
-is a chemical dissolved in water

stream bed
-is the bottom of the stream channel

stream capacity
-is made up of the total load that the stream or river is capable of carrying.
The capacity is measured in pounds or tons per hour of the load being carried by the stream or river.

stream competence
-is the largest object, such as a rock, that the stream is capable of moving.
-stream competence-Opal's Pals

stream cross section
-is a sectional view of the stream channel developed at right angles to the direction of stream flow.
-stream cross section diagram

stream energy
-A stream obtains its kinetic (moving) energy from dropping in elevation (gravitational potential
energy) as it travels.
-stream energy-Opal's Pals

stream gradient
-is the rate at which the stream or river drops in elevation per mile traveled.
-stream gradient-Opal's Pals

stream load
-consists of all of the materials being carried by the water in a stream.
Stream load includes bed load, suspended load, and dissolved load.
-stream load-Opal's Pals

stream piracy
-By head ward erosion one stream cuts into another stream, thus diverting the second stream's water
into a different drainage basin.
-example of stream piracy

stream terrace
-is a flat surface above an incised stream channel, formed when the stream went from a depositional
mode creating valley fill to an erosional mode.

stream velocity
-is a measure of how fast the water in the stream is moving.

suspension
-Small clay particles in turbid water are said to be in held in suspension by chaotic, turbulent flow and
buoyancy.
-clay in suspension-Sedona, Arizona 
-suspended load-Opal's Pals

traction
-is the pushing or pulling effect of moving water.

trellis drainage
-is a modified dendritic (tree-like) drainage pattern where many of the stream branches run parallel to a single
direction, influenced by a series of regional folds or a regional fault system.
-trellis drainage pattern diagram

tributary
-is a smaller stream that feeds into a larger stream; the term may also apply to rivers that feed into larger
rivers and small valley glaciers that feed into larger valley glaciers.

turbid
-occurs when sediment is stirred up in water making it look muddy or clouded.
-clay in suspension-Sedona, Arizona 

turbulent flow
-is chaotic stream flow; the opposite to smooth laminar flow.
-Poudre River-rapids 
-Yellowstone River-rapids 
-turbulent flow-Opal's Pals

V-shaped valley
-indicates a valley recently carved by a river.  It is considered to be an indication of a river in the youthful part
of its cycle of development.
-V-shaped valley, Halemahina volcano, Maui, Hawaii

waterfalls
-occur when the flowing water in a stream or river goes into free fall over a cliff.
-Niagara Falls, New York-American Falls 
-Yellowstone Falls 
-small waterfall in Maui, Hawaii