Problem: -  As water expands it puts great pressure on the walls of anything containing it, including any rocks which happen to be surrounding it - The force of the pressure exerted on the rock surrounding it is enough to wedge the walls of the crack farther apart, thus expanding and deepening the crack - Clay expends when wet like ice does - This causes rock to break apart - Some plants like mosses and lichens are capable of growing without soil on bare rock - When they do this their roots penetrate pores and crevices and cause rocks to split apart as the roots force their way down through the rocks -   What might be the first step of the process?

A: When water freezes it becomes 10% bigger, or takes up 10% more space


Problem: -  Sulfur in the coal combines with oxygen to form sulfur oxides - The sulfur oxides are released into the atmosphere - The sulfides combine with oxygen in the atmosphere to form sulfur trioxide - The sulfur trioxide reacts with water in the atmosphere to form sulfuric acid, a very strong acid - The sulfuric acid makes the rain acidic -   What might be the first step of the process?

A: Coal is burned


Problem: -  The movement is due to a combination of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained - Sediment transport occurs in natural systems where the particles are clastic rocks (sand, gravel, boulders, etc.), mud, or clay - The fluid is air, water, or ice - And the force of gravity acts to move the particles along the sloping surface on which they are resting - Sediment transport due to fluid motion occurs in rivers, oceans, lakes, seas, and other bodies of water due to currents and tides - Transport is also caused by glaciers as they flow -   What might be the first step of the process?

A: Sediment transport is the movement of solid particles (sediment)


Problem: -  The trees and plants burn - The animals lose their homes - If the animals can not escape, they may die from smoke inhalation - The plants that provide food are gone - The animals have little to eat -   What might be the first step of the process?

A: