Transgressive Coastlines

Question 1

A > S means sea will ….. so the sediment will ….

Answer 1

Transgress, the sediment will be eroded inland.

Question 2

A < S means sea will ….. so the sediment will …

Answer 2

Receed, so the sediment will prodgrade outwards into the sea.

Question 3

Name the succession of environments going out to sea during the building of a delta

Answer 3

Backshore, foreshore, shoreface, inner shelf, outer shelf

Question 4

When does sediment get preserved during flooding of the land?

Answer 4

Sediment can only be preserved when A

Question 5

What does TSE stand for? Discuss TSE.

Answer 5

Transgressive Surface Of Erosion, occurs during transgression inland where a surface is eroded. It starts when transgression starts and ended when regression begins.

Question 6

Evidence of alot of bioturbation is due to what?

Answer 6

Low sedimentation rates, it is not always because there are more organisms present.

Question 7

In the sedimentary record we see mostly evidence of regression or transgression?

Answer 7

Regression, transgression is rarely preserved.

Question 8

what happens to a barrier island during transgression?

Answer 8

It will get flooded and eroded away. It will build out if it is regression.

Question 9

Breaches in barrier islands are caused by what?

Answer 9

Tidal currents, as the tide rises you can get a flow that breaches the barrier island and so can get flood-tidal deltas.

Question 10

What is the difference between a flood-tidal delta and a delta?

Answer 10

Flood tidal deltas are formed at barrier islands when they breach due to a release in confinement. They do not form in the same way as a normal delta.

Question 11

Where are estuaries defined in a sedimentary point of view?

Answer 11

Defined by the Inner Limit of Tidal Influences (ILTI)

Question 12

What does ILTI stand for

Answer 12

Inner Limit of Tidal Influences

Question 13

Discuss the balance of energy in the estuary process

Answer 13

At the sea end marine processes as dominant, as you go inland they become progressively weaker until they reach 0. At the river end the river is the most dominant process, and as you move further towards the sea it becomes less dominant.
The arbitrary point is where they cross, 50 energy from sea and 50 energy from river.

Question 14

Low tidal range and exposed coastline gives you a …. dominated estuary

Answer 14

Wave

Question 15

Tide dominated estuaries have …. tidal range and coast is …. with ….. waves.

Answer 15

High tidal range, coast is sheltered with weaker waves

Question 16

discuss a river dominated estuary

Answer 16

This is not possible as the river would fill up the valley and create a delta. The river may dominate over a short period of time.

Question 17

Discuss a tide dominated estuary as much as you can.

Answer 17

Tidal inflow and outflow much stronger, waves are minor and drop off very quickly. Tidal flow speeds up as it funnels into the estuary, once they are into the estuary they drop off. River flows are the opposite to this and pick up once you are in the estuary. The red line on the diagram shows the relative energy which drops when the river is meandering.
Sand bars are present at the mouth, they are elongated parallel to the dominant flow current. Aligned in direction to valley and parallel to valley axis.

Question 18

In a tide dominated estuary, are the sand bars parallel or perpendicular to the valley axis?

Answer 18

Parallel to valley axis

Question 19

In a tide dominated estuary, are the sand bars parallel or perpendicular to the valley?

Answer 19

They are aligned in the direction to the valley so are perpendicular.

Question 20

Why would the flow come in one side of the estuary and go out another? what does this mean for sedimentary structures at either side of the estuary

Answer 20

Because of the way the moon pulls the tide. At one side there will be a unidirectional current creating dunes whilst the other side will have dunes migrating in the other direction.

Question 21

what happens when saline and river water mix with clay particles present?

Answer 21

The clay particles clump together (flocculate) due to the changing salinity and drop to the seabed as they can’t be carried in suspension