The Mesozoic Flashcards
Which periods divide the Mesozoic era?
Triassic, Jurassic, Cretaceous
What is the time frame of the Mesozoic?
251Ma to 65Ma
By the end of the Mesozoic what is the situation regarding position and shape of Britain?
Very similar latitude to today, and similar continent layout.
What major world event precedes the Mesozoic? What does this mean for the Triassic?
The Permian extinction, so life starts afresh in the Triassic.
What type of life dominates the Triassic period?
Lizards
What are the two main rock types found from the mesozoic?
Limestones and Mudstones
Where are Mesozoic rocks most commonly found?
Midlands and South - some in North East. More western earlier in the era.
What do the varying levels of Calcium in oceanic rocks tell us?
The type of oceanic environment they formed in, e.g depth.
What iconic geological feature owes its origin to the Cretaceous period?
White cliffs of Dover.
What major world event marks the end of the Mesozoic?
Mass extinction at the end of the Cretaceous, extinction that killed the dinosaurs.
What are some possible environmental causes of mass extinctions?
- Climate too hot or cold: sea levels rising or falling.
- Ocean anoxia: reduction in oxygen in oceans due to atmospheric or circulation changes.
- Higher levels of volcanism and volcanic gas.
Was the cretaceous extinction gradual or quick?
Slower for oceanic life which had been declining for approx 1 million years prior. Quicker for surface organisms.
What rock types are most common for the Triassic period?
Mudstones, calcareous or silty mudstones.
What rock types are most common from the Jurassic period?
Mudstones and limestones - especially oolitic limestones.
Lots of fossils.
What rock types are most common from the Cretaceous period?
Limestones and chalks.
