A geologist is looking at deposits along a river below a large volcano.She finds large boulders mixed with sand and mud,and all of the material is comprised of volcanic rocks,particularly the mud which is volcanic ash.She quickly realizes these deposits represent an ancient ________.
A)earthflow
B)rock avalanche
C)slump
D)lahar

Question

Quizplus · Accepted Answer

The presence of large boulders mixed with volcanic ash and mud indicates that these deposits were formed by a fast-moving volcanic mudflow called a lahar. This type of deposit is common in areas near active volcanoes and can be dangerous for nearby populations. Earthflow, rock avalanche, and slump are all types of landslides but do not involve volcanic materials.

A Geologist Is Looking at Deposits Along a River Below