Streams sand grains at lower velocities and velocities a. erode; deposit b. depo
ID: 118246 • Letter: S
Question
Streams sand grains at lower velocities and velocities a. erode; deposit b. deposit; erode c. transport; deposit d. erode; transport Streams sediment at the inside of bends and outside of bends. C sediment along the a. erode; deposit b. deposit; erode c. transport; deposit d. erode; transport XA delta orms when water flowing through a stream reaches a(): c. mountain. d. A and B. ocean. Given the same discharge, which stream will have the highest velocity? a. narrow, shallow b. wide, shallow rough channel all will flow at the same velocity As river water moves from headwaters to base level within a fluvial sytem, its energy (-speed)and the average sediment size it can carry a. decreases; increases c. increases; increases d. increases; decreases What fluvial deposit is generated due to overflow of water from the stream channel to the floodplain? a. an alluvial fan b. point bar deposits c. natural levees deltas Biological sediment includes: a. quartz. b. sand. pebbles. d. shells. Well-rounded sediment suggests the sediment has been: a. transported a long distance. b. transported a short distance. c. not transported at all. d. transport distance cannot be determined. The occurrence of conglomerate, sandstone, and mudstone with asymmetrical ripples, mudcracks, and root traces suggest a environment. a. desert b. river and floodplain c. deep ocean d. reef cont'dExplanation / Answer
1) Streams DEPOSIT sand grains at lower velocities and ERODE them at higher velocities.
2) Streams DEPOSIT sediment at the inside of bends and ERODE sediment along the outside of bends
Reason – The stream velocity is low at the inside of bend and high at the outside of bend.
3) A delta forms when water flowing through a stream reaches a LAKE or an OCEAN (A & B)
Examples – Volga delta (Caspian sea – It’s just a big lake), Mississippi delta (Atlantic Ocean)
4) Given the same discharge, a NARROW and SHALLOW stream will have the highest velocity
Reason – Discharge = Area x Velocity; Therefore Velocity = Discharge/Area
Now, Discharge is the same according to the data - let’s assume it to be 1000 m3/sec
For wide river – let the width be 1000m and depth be 1 m - Area = 1000x 1 = 1000 m2
For narrow river – let the width be 100m and depth be 1 m – Area = 100x1 = 100 m2
Now, putting values in the equation – Velocity (V) = 1000/1000 = 1 m/sec for wide, shallow river
Whereas Velocity (V) = 1000/100 = 10 m/sec for narrow, shallow river
Therefore, Narrow, shallow river will have max velocity.
5) As river water moves from headwaters to base level within a fluvial system, its energy (speed) DECREASES and the average sediment size it can carry also DECREASES
6) NATURAL LEVEES are generated due to overflow of water from the stream channel to the flood plain.
Example – Mississippi levees. As flood water overflows the banks, sediment is deposted along the banks. Subsequent deposition and consolidation of sediments result into the formation of Levees.
7) Biological sediment includes SHELLS.
Anything that has an organic origin falls under Biological sediment category. Shells once formed a part of invertebrates like bivalves, echinoderms or gastropods. Hence they have a biological origin.
8) Well-rounded sediment suggests that the sediment has been TRANSPORTED A LONG DISTANCE.
Reason – Longer the distance of transportation, greater the attritional, corrasional, saltational effect of river water and sediments on the pebbles. This gives a rounded definition to the pebbles in the long run. Also smaller the pebble size, lesser the distance required for rounding.
9) The occurrence of conglomerate, sandstone and mudstone with asymmetric ripples, mudcracks and root traces suggest RIVER AND FLOODPLAIN environment
Evidences – Conglomerate and sandstone, Unidirectional flow (Hence asymmetric ripples), root traces and mudcracks = river bank environment.