2.4 Gelogical History Of UK Flashcards
How have the British isles moved over last 500 million years?
Last 500 million years moving from near South Pole to current location
Explain features of the Lower Palaeozic age?
Avalania is where UK was between Iapetus and Rheic seas
Main continent called Gondwana
450 million years ago
Strong turbidity currents with sandstone and mudstones
Structures are flame and load, graded bedding and flute casts
On land many explosive volcanic eruptions
Oregenic mountain ranges form due to continental collisions eg folding, faulting like reverse/thrust faults
Granite plutons form in the root of mountain ranges
What are the features of the Upper Palaezoic age?
400 million years ago
Closer to the tropical latitudes at coast
Lots of coal production in tropical swamps
Mature sandstones and mudstones underneath coarser sand in swampy conditions
What are the features of the Mesozoic age?
Means greenhouse conditions as water floods onto land
Lots of shallow seas
Warm climate leads to lots of limestone
On land deserts form and produce red desert sandstone with red oxidised rocks and dunes and large scale crossbeds
What are the features of the Cenozoic age?
Atlantic Ocean opened during flood basalt event creating British tertiary province eg giants causeway
Widespread glaciation
Till deposited, bolders with clay, angular and poorly sorted
Unstratified with no bedding
What are the features of ice paleo - environment?
U shaped valleys with flat bottoms, steep sides and rocks with scratched surfaces facing direction of the valley
Formed by glaciers, picking up everything and depositing
600 million years ago near South Pole
Rock forms, angular, coarse grained, poorly sorted
What are the features of desert paleo - environment?
Rocks are rounded and very small 1.2 mm medium grained
Desiccation cracks and cross bedding
Caused by lots of erosion and transport
Desiccation in dry places
Cross bedding formed in deserts
450 million years ago near tropic of Capricorn
What are the features of tropical rainforest/marine palaeo - environment?
Lots of coral
Calcite
Trilobites and ammonites (very rare)
Coral found in tropical seas and environment
Calcite caused by evaporation in tropical environments
Trilobites crawl on the sea floor
300 million years ago near equator
What are the features of Savannah/tropical grassland palaeo - environment?
Lots of coal mined to generate electricity and warm homes
Submerged forests and roots of mangrove forests
Coal formed in deltas and swamps
Sea level rises when forests submerge
230 million years ago near tropic of cancer
What are the features of temperate forests palaeo - environment?
V shaped valleys Subrounded moderately sorted rocks 2mm Small crossbeds Valleys caused by rivers Small crossbeds caused by ripples 100 million years ago near current location
