Coasts - 2B.2 Flashcards
Geology: resistant rock coastlines
- In the south west, Cornwall bears the brunt of the worst weather from the Atlantic. Due to its geology, Cornwall can withstand the winter storms without eroding. It’s made of older and more resistant rocks such as igneous (basalt and granite), older sedimentary (old red sandstone), metamorphic (slate and schists) and these re all resistance to the erosive power of the sea, wind and rain.
Lithology definition
chemical and physical characteristics of rock type
Rock structure definition
physical characteristics - jointing, bedding, faulting, angle of dip
High energy coastlines
- very powerful waves
- erosion > deposition
- erosional landforms - headlands, cliffs, shoreline platforms
- Eg. Cornwall and North West Scotland
Low energy coastlines
- less powerful waves
- deposition > erosion
- depositional landforms - beaches, spits, coastal plains
- Eg. Lincolnshire coastline and Northumberland coastline
Metamorphic rock types
- slow erosion
- Eg. Slate, schist and marble
- changed due to heat or pressure - may now be crystalline - no bedding planes but may have foliation (all crystals same way) = weak. They can be heavily folded and faulted making it even weaker
Sedimentary rock types
- moderate/fast erosion
- Eg. sandstone, shale, and limestone
- Clastic (made of smaller pieces), sediment laid down over time in bedding planes, joints between layers - weak points
- Shale is easily eroded and has many bedding planes
Igneous rock types
- very slow erosion
- Eg. granite, basalt and dolerite
- made of crystals that are interlinked and may have cooled slowly over thousands of years
- there are no natural weak points
- forms headlands
Strata definition
layers of rock
Bedding planes
areas of contact/gaps between the layers
Fault definition
fractures along which movement occurs
Joint definition
fractures along which no movement has occurred
Dip definition
refers to the angle at which a rock strata lie (horizontally, vertically, dip towards the sea or land)
Folds definition
formed by pressure during tectonic activity
Geology: Coastal plain landscapes
- eastern and southern Britain has a weaker and younger geology - chalks, sand, sandstone. Low energy so waves aren’t as strong. Deposition > erosion
- the Wash - areas of low, flat relief referred to as a coastal plain. Theres a range of habitats - tidal creeks to music flats, salt marshes and lagoons
- much of the eastern coast consists of low-lying sandy beaches eg. Bamburgh beach in Northumberland
Discordant coastlines
- the rock the runs perpendicular to the coastline
- Eg. clay/sands - chalk - clay/sands - limestone on the east Dorset coast
Concordant coastlines
- the rock type runs parallel to the coast
- Eg. limestone forms the concordant coastline on the South Dorset Coastline
Haff Coastline
- Southern fringes of the Baltic Sea
- Concordant coastline
- long sediment ridges topped by sand dunes run parallel to the coast just offshore creating gaffs (lagoons) between the ridges and shore
Geology of the UK
South East and East
- softer rock like chalk and clay
South West and North
- harder rock like basalt
Dalmation Coastline
- Croatia in the Adriatic Sea
- drowned by sea level rise during the Holocene. The anticlines and synclines (strata dip) that are parallel to the modern coast
- Underlying structure of upstanding anticline and lower syncline basin (would have been eroded by the rivers in the past) has been drowned by rising sea levels
- Concordant coastline of long, narrow islands offshore
