STRATIGRAPHY AND SEDIMENTATION (RUNNING WATER AND GROUNDWATER) Flashcards
The unending cycle of water on Earth
Hydrologic Cycle
How much is the water content of the hydrosphere?
1.36B cu.km. / 326M cu.mi
Ocean Component
97.20%
NonOcean component
2.80%
Glaciers
2.15%
Gwater
0.62%
Fwater Lakes
0.009%
Saline Lakes and Inland Seas
0.008%
Soil Moisture
0.005%
Atmosphere
0.001%
Stream Channel
0.0001%
Liquid changes into water vapor and is how water enters into the atm from the oceans
Evaporation
Water soaks into the ground
Infiltration
Thw flow of surplus water over the surface
Runoff
The process by which plants release its absorbed water into the atmosphere
Transpiration
Combine processes that transfer of water from the surface directly into the atmosphere
evaportranspiration
The single most important agent sculpting the Earth’s land surface
Moving Water
Stages of Runoff
Sheet Flow - Rills - Gullies- Streams - Rivers
The land area which contibutes water to a river system
Drainage Basin
What divides the drainage basin of a particular river to that of the draiange basin of another basin?
Divide
This type of divide splits the whole continent into enormous drainage basin
Continental divide
Larget drainage basin in North Am
Mississippi River
This involve not only a newtork of stream channels but the entire drainage Basin
River systems
Three Division of River Systems in reference to sediments?
1) Sediment Production
2) Sediment Transport
3) Sediment Deposition
This is also known as the river’s source of the farthest place in that river or stream
Headwaters
This is the zone where most sediments are produced because of extensive erosion and is located in the headwater region of the river system
Zone of Sediment Production
This is the zone where sediments are displaced by mass wasting and/or overland flow
Zone of Transportation
These are the channel network along sections in which sediments are transported. They are not source of sediment, nor do they accumulate or store it
Trunk Streams
This is the Zone where river reaches the ocean or another large body of water and slows down affecting the transport of energy to be reduced
Zone of Deposition
What are the possibilities of deposition in River systems?
1) Seds can accumulate at the mouth of the river to form delta
2) Sediments can be reconfigured by wave action to form a variety of coastal features
3) Can be moved far offshore by ocean currents
Main principle of deposition in River systems?
Corse grained are deposited upstream while fine grained are the ones reaching the ocean
These are networks of streams that together form distinctive patterns
Drainage Patterns
What are the controlling factor of Drainage Patterns?
1) Type of Terrain
2)Kinds of Rocks
3) Structural pattern of folds and faults
Drainage pattern in relatively uniform surface thus is resistant to erosion and does not control the stream flow. Pattern is determined chiefly by direction of slope of the land
Dendritic Pattern
A drainage pattern that resembles a branching deciduous tree pattern
Dendritic Pattern
What does dendritic mean?
Treelike
This is the pattern when streams diverge from a central area like spikes from the hub of a wheel
Radial Pattern
Where does Radial pattern usually develop?
On Isolated volcanic cones and domal uplifts
This pattern is characterized by many right-angle bends and guides the direction of valleys
Rectangular Pattern
Where does Rectangular Pattern develop?
On bedrock is crisscrossed by a series of joints and/or faults which makes them more easily eroded
This is a rectangular draianage pattern in which tributary system are nearly parallel to one another
Trellis Pattern
Where does Trellis pattern develop
On areas underlain by alternating bands of resistant and less-resistant rock
Flow characterized by roughly straight-line paths that are parallel to the stream channel
Laminar Flow
Flow in which the water moving in an erratic fashion that can be chracteried by swirling motion
Turbulent flow
If a stream appears to be smooth on the surface, does it mean it is laminar flow?
No
Relation of strength of current/Velocity and depth
The deeper the parts of the channel the stronger the current
Why is it so?
Because frictional resistance is greaterst near the banks and bed of the stream channel
Factors which controls Flow Velocity and the ability to erode and transport material
1) Channel slope or Gradient
2) Channel size and Cross sectional shape
3) Channel Roughness
4) Amount of Water Flowing
the vertical drop of a stream over a specified distance
Gradient
What is the velocity if gradient is high?
High
What size of a channel has more efficient flow?
Larger
What kind of channel has a uniform flow?
Smooth
Volume of water flowing past a certain point in a given unit of time
Discharge
Formula of Discharge
Stream’s Cross Sectional Area x Velocity
Largest river in N America
Mississippi River
World’s largest River
Amazon River
Discharge of Amazon
Approx 207,000 cu m
Streams which exhibit flow only during wet periods
Intermittent Streams
Streams which carry water only occasionally after a rainfall in aird climates
Ephemeral Streams
A cross sectional view of a stream from its source area to its mouth
Longitudinal Profile
Source area of a river
Headwaters
Point where a river enters another body of water
Mouth
the shape of the typical profile of a river?
Concave
Whats the X and Y axis of a longitudinal profile?
distance (X) Elevation (Y)
As a river decreases in slope, what happens to discharge and roughness?
Discharge increases and sediment particeles dicreases thus river becomes smoother
why is a river more efficient downstream?
Because increase in channel size and increase in discharge and smoothnes compensates the decrease in gradient
Sequence of stream Erosion
Rainwater - Sheetflow - Rills - Gullies - Streams - Rivers
Bowl-shaped bedrock depressions caused by abrasion of whirlpool of sand and pebbles
Potholes
sediments that is in solution with the water
Dissolved Load
Largest part of a stream’s load usually made up of silt and clay
Suspended Load
Factors affecting suspended load
Flow velocity and Settling Velocity
In terms of shape which particle settles faster?
Spherical grains
Coarse sediments that move along the bottom of the stream
Bed load
Types of bed load movement
Rolling, Sliding, Saltation
Movement through jumping or skipping along the bed
Saltation
etymology of Saltation
Saltare - To leap
The maximum load of solid particles a stream can transport per unit of time
Capacity
A measure of stream’s ability to transport particles on size rather than quantity
Competence
What’s the relationship between competence and stream velocity
Competence increases proportionately to the square of its velocity
When does capacity increases?
when discharge increases
When does deposition start to occur?
When flow velocity < Settling velocity
The meachanism by which solid particles of various size are separated
Sorting
General term for stream deposits
Alluvium
Sheetflow vs streamflow?
Stream flow is confined to a channel
An open conduit that consists of stream bed and banks that act to confine the flow except during floods
Stream Channel
Channels that are actively cutting into solid rock
Bedrock Channel
Streams that are actively cutting into unconsolidated sediments
Alluvial Channel
What are the characteristics of Bedrock Channel
Headwaters, Coarse grained, abrasion, potholes
Steep segments where bedrock is exposed which usually contain rapids or waterfalls
Steps
Relativey flat segments where alluvium tends to accumulate
Pools
Major factors affecting alluvial channels
Size of sediment transported, channel gradient, and discharge
Alluvial channels in which transport is usually suspension and are relatively deep and smooth because the sediments are mostly silt and clay
Meandering Streams
Sweeping bends of a river
Meanders
This is the outside of a meander where erosion is mostly focused where velocity and turbulence are greatest
Cut Bank
The inside of meanders where coarser material is deposited
Point bars
a new shorter channel segment formed by erosion due to slowing of downstream migration
Cutoff
The abandoned bend of a meandering stream
Oxbow Lake
Streams composed of a complex network of converging and divering channels that thread their way among numerous islands or gravel bars which consist mostly of coarse materials an the stread has highly variable discharge and are usually wide and shallow
Braided Channels/ Streams
Where do braided channels usually form?
At the terminus of a glacier
Consist not only of channel but also the surrounding terrain that directly contributes water to the stream
Stream Valley
the lower flatter area of a valley occupied by stream channel
Valley Floor
Stream Valleys in arid regions where weathering is slow an where rock is particularly resistat resulting to nearly vertical walls
Narrow Valleys or Slot Canyons
The lowest elevation at which a stream can erode its channel
Base Level
The sea level which is also the lowest level at which stream can lower the land
Ultimate Base Level
This includes lakes, resistant layers of rocks, and main streams that act as base levels for tirbutaries
Temporary or local base level
What are the consequences of building a dam?
Base level is elevated
Gradient upstream is gentler or reduced
Eroding and transporting capability of stream reduced and deposition will be dominant
The dominant activity when a stream’s gradient is steep and the channel is well above the base level
Downcutting
A prominent feature of a V-Shape valley formed by resistant beds acting as a temporary base levelwhile allowing downcutting to continue downstream
Rapids
A prominent feature of a V-shaped valley formed where streams make an abrupt vertical drop
Waterfalls
The continuous lateral erosion cause by shifting of the stream’s menaders which profuces an increaringly broader, flat valley floor covered with alluvium
Valley Widening
A broad flat valley floor covered with alluvium
floodplain
meanders that form on steep, narrow valleys
Incised Meanders
Circumstances that changes the base level that led to the formation of incised meanders
1) Marine regresion
2) Land uplift
small scale deposits composed of sand and gravel
Bars
forms where a sediment-charged streams enters the relatively still waters of a lake, an inland sea or the ocean
Delta
Several small divisons of the main channel which carry water away from it
Distributaries
factors that affect the shape of the delta
Shoreline configuration and nature and strength of waves
Beds that are deposited above foreset beds during floods
Topset
Beds consist of coarse particles that drop soon after entering the water body
Foreset
Beds consist of fine silt and clay and are settled beyond the mouth of the river
Bottomset
how many deltas are there in the mississippi delta?
7
A coarse to finely sorted gently sloping landform bordering the channel on both banks build by successive floods over many years ago
Natural levees
the marshy area behind the levee which is poorly drained for the reason that water cannot flow up the levee and into the reaver
Back Swamps
A tributary that flows parallel to the main river until it can breach the levee
Yazoo Tributaries
To which river does Yazoo river flow parallel to?
Mississippi river
a fan shaped landform forms where a high gradient stream leaves a narrow valley in mountanous terrmain an comes our SUDDENLY onto a broad flat pain or velly floor
Alluvial Fans
Group of coalescing Alluvial Fans
Bajada
Conditions which form alluvial fans
Change of gradient and velocity and change in cannel size
A natural phenomenon occurs when the flow of stream becomes so great that it exceeds the capacity of its channel and overflows its banks and is considered to be the most dealy and the most destrucive of all geologic hazards
Flood
type of floods which are more limited in extent and occur with limited warning and can be dedly because they produce a rapid rise in water levels and can have a devastating flow velocity
Flash Floods
Factors which influence flash floods
1) Rainfall intensity and duration
2) Topography
3) Surface conditions
Earthen mounds built on the banks of a river to increase the volume of water the channel can hold and are the most commonly used stream-containment structures
Artificial Levees
how do artifical levees differ from natural levee
AL are much steeper and are sometimes made up of cocrete
These are structures built to store floodwater and then let it our slowly which can also be use for agricultural irrigation and hydroelectric power generation
Flood control Dams
this flood control measure involves altering a stream channel in order to speed the flow of water to prevent it from reaching flood height
Channelization
Flood control measure which involves straigthening a channel and shortnening the stream thus increaseing the flow velocity and gradient
Artifical cutoffs
