I believe it is Sand. because when sand hardens it's like a type of case that conceals things like bones hope this helps and have a great day :-)
The correct answer is - B. Ice movement and deposition of eroded material.
During the last Ice Age, that finished around 10,000 years ago, the Alps were covered in snow and ice, and lots of glaciers. The movement of the numerous glaciers was the main factor behind the formation of the Alpine landscape features that we see nowadays. The glaciers made numerous valleys, cirques, U-shaped valleys, aretes, pyramidal peaks, truncated spurs. As the Ice age ended, all of these landscape features were revealed once most of the glaciers were gone, and we got the landscape that we see on the Alps in the present.
The plates — interlocking slabs of crust that float on Earth's viscous upper mantle — were created by a process similar to the subduction seen today when one plate dives below another, the report says. ... Other researchers have estimated that a global tectonic plate system emerged around 3 billion years ago.
