What most likely happened in sediment layer 5?
a massive volcano erupted, causing global warming and
lava flow, which in turn caused mass extinction
more iridium was produced by space objects and
dumped by local factories.
a massive dust cloud formed, causing global cooling
and a lack of sunshine. this in turn caused a lack of
plants and a mass extinction
fewer impacts lead to a drop in iridium levels and a
mass extinction caused by a lack of sunshine