Question

an iridium-rich layer of clay, glass spherules, and shocked quartz grains marks the extinction event at the end of the

a) permian

b) cretaceous

c) ordovician

d) triassic

e) devonian

Answer 1

an iridium-rich layer of clay, glass spherules, and shocked quartz grains marks the extinction event at the end of the

b) cretaceous.

An iridium-rich layer of clay, glass spherules, and shocked quartz grains strongly suggests that the K-T (Cretaceous (K) and Tertiary (T)) boundary extinctions were caused by the impact of a bolide (meteoroid or comet). In this event more than three-fourths of all plant and animal species living on Earth became extinct. The most famous group of animals to extinct was the dinosaurs.