Choose all of the following possible causes for the Ordovician-Silurian extinction. Select all that apply.
Climatic cooling
Major glaciation
Global warming
Sea level drop
Increase in ocean pH

Climatic cooling, Major glaciation, Sea level drop are the following possible causes for the Ordovician-Silurian extinction.

Option: A, B, D

Explanation:

In geological time scale Ordovician and Silurian are the epoch of Mesozoic era. Others are Devonian, Carboniferous and Permian. Almost 300-400 B.C. ago these periods were in work. Each of the epoch and period has their own characteristics regarding plant and animal life like Carboniferous was famous for the formation of coal.

There is a some sorts of natural reason for the extinction or discontinuation of each period and introduction of new period in geological time scale. Major glaciations mean accumulation or solidification of snow at large scale due to extreme cooling which causes reduction of sea level height.

map scale refers to the relationship (or ratio) between distance on a map and the corresponding distance on the ground. for example, on a 1: 100000 scale map, 1cm on the map equals 1km on the ground.