geological structure (2.B2)

Question 1

coastal morphology definition

Answer 1

is the shape and structure/ form of coastal landscapes and their features
- geological structure (rock arrangements) + bedrock lithology (rock properties/ characteristics) = coastal morphology

Question 2

bedrock lithology (6 characteristics)

Answer 2

geological structure is an important influence on coastal morphology, erosion rates and occurrance of micro features. (also on the formation of cliff profiles)

1. strata (layers of rock)
2. bedding planes (horizontal natural breaks in the strata caused by gaps in time during periods of rock formation)
3. joints (vertical fractures caused by either contrcation as sediment dries out or by earth movemnts during uplift)
4. folds (formed by pressure during tectonic activity which makes rocks buckle/ crumple EG the Lulworth Crumple)
5. faults (stress or pressure subjected to a rock that exceeds its internal stength causing it to fracture and slip/ move)
6. dip (angle at which rock strata lie: horizontally/ vertically, dipping towards sea/ inland)

Question 3

cliff profiles (6 mark question)

Answer 3

how to answer:

1. describe what you see:
   - strata (how many layers/ types is there?)
   - describe its profile: the slope of the cliff (eg verticle, gentle, stepped)
   - note any extra details eg headland/ bays? any scree at base?
2. explain the reasons effects
   - impact of rock types on cliffs structure
   - what has been more influential? subaerial or marine- how can you tell?
   - basically say WHY the cliff looks like it does: subject to any erosion/ mass movement?

Question 4

concordant coastlines

Answer 4

generated when bands of varying resistancy run parallel to the coastline
EXAMPLE: Lulworth Cove, Dorset
- hard Portland limestone and fairly resistatant beds protect softer rock landward
- however faults in these resistant rock bands allows marine erosion to break through and then rapidly erode the rock behind forming wide coves (eg Lulworth Cove and Warbarrow Bay)
- at the back of these coves is resistant chalk which prevents erosion further inland

other types of concordant:
1. Dalmation Coast (Croatia)
formed as a result of sea level rise (after the holecene)
- valleys and ridges run parellel to each other but the valleys are submerged by the sea so only tops remain above sea level: now a series of islands that run parellel to the coast

2. Haff Coasts
   named after the southern shore of the Baltic Sea
   - consists of long spits of sand that run offshore parallel to the coast creating lagoons (Haffs) between the ridge and the shore.

Question 5

discordant coastlines

Answer 5

formed when different rock strata intersect the coast at an angle so geology varies along the coastline
dominated by HEADLANDS and BAYS:
- less resistant are eroded to form bays whereas more resistant geology remains as headlands
- at headlands, water becomes shallower increasing wave height. waves are forced to refract or bend increasing their erosive power (more concentrated) which leads to steepening and eventual erosion of cliffs
- at bays, water is deeper so energy is dissipated and reduced which leads to deposition of sediment forming a beach
EXAMPLE: Clear Island
often esecially resistant areas of headlands remain as detached islands.
- on Clear Island, long narrow bays= drowned river valleys