coasts L2 Geology and Coastal Morphology Flashcards
Factors Affecting Rate of Erosion
- Wave Type & Breaking Point
- Fetch
- Sea Bed Depth & Profile
- Coastline Shape
- Beach Presence
- Human Impacts
What is the variation in rates of erosion between rock types known as
Differential Erosion
Rock Types from most resistant to least resistant
(beach slate, chalk, pillow lava/basalt, granite pebbles, unconsolidated material)
Most
Basalt/Pillow Lava (Igneous)
Granite Pebbles (Igneous)
Beach Slate (Metamorphic)
Chalk (Sedimentary)
Unconsolidated material - till, sand, gravel
Least
Basalt Details
erodes 1-3mm per year
IGNEOUS rock - most resistant
made all in one go during an eruption - no faults that would create weakness
forms when lava cools from exposure to air or water (millions of years ago)
Slate details
erodes 1cm per year
METAMORPHIC - medium resistance
formed from sedimentary or igneous rock being put through intense heat and pressure
Chalk & Limestone Details
(calcium carbonate) - brain coral is the weakest form (porous)
erodes 2-10 cm per year
sedimentary - med/low resistance
formed on seabed as a collection of broken down rock sediments and shells from dead sea creatures
takes millions of years to form and then shift towards the land again due to tectonics
Unconsolidated Material Details
erodes 2-4m per year
not a rock - low resistance
glaciers during the Ice Age grind up rock and mix it with mud and when the snow and ice melt away they leave behind the mudstone underneath
superficial deposits - just sediment that should technically be left to erode away
Concordant Coastlines
direction of waves is PERPENDICULAR to the geology lines
the actual like face of the wave is parallel though x
STRAIGHT COASTLINES
Cliff of Dover
Discordant Coastlines
the direction of the waves is PARALLEL to the geology lines
face of wave is perpendicular
WONKY coastlines
Swanage Bay, Dorset
Bedding Plane
HORIZONTAL weakness between rock layers
Fault
MAJOR weaknesses within rock layers
Fissures
smaller cracks in rocks (few cm or mm)
Strata
different layers of rock within an area and how they relate to each other
Joint
VERTICAL weakness
