streams/ meanders/ some fossils Flashcards
streams
Any body of water with a current (brooks,creeks,rivers)
- Moving water is the most erosive force on earth - Always flows downhill
Tributary water system
A system that flows into a larger system
watershed water system
The geogrpahic area drained by a particular river or stream
stream erosion features
V-shaped Valley, Meanders (stream with curves that develop when a stream flows over flat land)
stream deposition features
Delta, Oxbow ,Flood plain, levee
Delta
A delta is a region at the end (mouth) of a stream or river that consists of sediments deposited as the velocity of the stream decreases (horizontal sorting)
Oxbow lake
U shaped body of water that forms when a wide meander from the main stem of a river is cut off, creating a free-standing body of water
Flood plain
Flat region next to a stream or river that may be covered by water in times of flood
Levee
Streams in broad valleys sometimes flood and leave deposits of sand and silt on the land bordering and parallel to the streams
How younger streams change over time
steep slope, high erosion, V shape
How old streams change over time
Flat wand, slow moving (flood plain), high deposition (levees, Oxbow, Deltas), Meanders
straight stream
Water moves fastest in the middle just below the surface
Meander
outside of curve: Fastest,erosion,deeper
inside of curve: slower, despostion, shallow
Glaciers (Movement of Ice)
: a naturally formed mass of ice and snow that moves downhill on
land under the influence of gravity
Continental glacier
glaciers that form at high latitudes and flow outward to cover a large part
of a continent.
Valley glacier
glaciers that form at high elevations when ice flows downhill as snow
accumulates and changes to ice.
Glaciers will _________when there is more snow accumulating than melting.
advance (move forward)
Glacier will __________ when there is more melting than snow accumulating
retreat (move backward)
Striations
Evidence of glacial erosion/parallel scratches on bedrock
- Formed when rocks that are transported on the bottom of the glacier leaves scratches
and grooves in the bedrock over which they pass. - Indicate the direction the glacier moved
U-shaped Valley
evidence of glacial erosion/
when a glacier moves down a mountain valley, the glacier and its load of
sediment pluck, scrape, and scour the sides of the valley changing its profile to a broader
U-shape
What landscape features are evidence that glaciers deposited sediments
till, moraine, outwash plain, drumlin, Kettle lake, Erratic
Till
unsorted, unlayered glacial sediments that are deposited directly by a glacier
Moraine
a hill of till deposited directly from an edge or bottom of a glacire
Outwash plain
horizontal sorted layers of glacial material in front of the glacier, formed
by the meltwater of the glacier
Drumlin
Drumlin: glacial hills of unsorted, unlayered sediment that are shaped like the back of a
spoon by the ice
Kettle lake
when blocks of ice are left behind, form a depression, and melt
Erratic
Erratic: rocks that have been transported to an area (type of rock not normally found in
that area
relative age
The age of rocks or events compared to the age of other rocks or events
absolute age
The age of a rock object or event in years
uniformitasim
The geologic processes that took place in the past are generally similar to those that take place now
Principle of original horizontally
Sediments are deposited in horizontal layers that are parallel to the
Surface they were deposited on
principle of superpostion
In undisturbed layers, the oldest layer is
On the bottom and each
Overlying layer is younger
Igenous intrusions/ Extrusions
As hot magma squeezes into cracks and zones 0f weakness
The cooling magma passes its heat energy to the nearby rock
erosion
Carrying away of weathered rock materials
unconformity
A gap in the rock record cause by the burial of an eroded surface by younger sediments shown on rock outcrop by a wavy line
folding
Layers of sedimentary rock that have been bent or warped by crustal forces
Tilting
Formally horizontal rock layers that have been tilted at an angle by crustal activity
faulting
A crack of weakness in earths crust along which movement occurs during an earthquake
law of cross-cutting
A distruption that cuts through rock or another geologic feature must be younger than the rock or other geologic feature
index fossils
Fossils of organisms that lived over a wide geographic area for a relatively short period of time
