What is the thick, old crust of earth known as?

You have been tasked with sorting the rock samples shown into three categories, with two rocks in each category. what attribute would you use to sort these rocks? which rocks would be in each category? rocks: obsidian, coquina limestone, granite, soapstone,pumice, and gneiss.

Which of the following is an example of relocation diffusion

A2 cm object is 10 cm from a convex lens that has a focal length of 4.4 cm, the image is 8cm from the lensz the height of the image, to the tenths place is