The types of unconformities that can occur in rock layers are: ANGULAR, NONCONFORMITY and DISCONFORMITY.
The answer is an overhunting.
<span>The bottleneck event means drastic reduction of the population size because of environment changes. The consequence of this is the reduction of genetic variation. The bison population is a good example of the population bottleneck. The bison population drastically reduced its size due to overhunting which culminated at the end of the 19th century, when bisons almost extinct. </span>
