Answer:
A sinkhole lake forms by The formation begins with the subsurface dissolution of limestone, ultimately leading to surface collapse. As sediments are washed into the depression, the sinkhole becomes plugged.
CMEs. Coronal mass ejections
Acid rain from Los Angeles changed the chemistry of the river, resulting in the death of many fish.Due to human activities in Los Angeles, pollution is not anymore shocking. The acid rain would be distributed to the river which would change the environment of the aquatic life.
They did this because the goths needed somewhere to stay the Roman Empire offered to help out
