Master Weathering and Erosion with Earth Science review games.

A granite boulder in a cold climate develops a crack. Water seeps in, freezes each winter, and over 50 years the boulder splits into two pieces. What type of weathering is this and why?

This is mechanical (physical) weathering via freeze-thaw or frost wedging. Water entered the crack in liquid form, then froze and expanded, exerting pressure on the rock walls. Because the granite is now just two smaller pieces of granite — no new minerals were formed — the chemical composition is unchanged, confirming it is mechanical weathering.

A limestone cave forms underground over thousands of years. What chemical process is responsible and what is the chemical agent involved?

Carbonation is responsible: rainwater absorbs CO₂ from the atmosphere and soil to form weak carbonic acid (H₂O + CO₂ → H₂CO₃). This acid reacts with the calcite in limestone, dissolving it and carrying it away in solution. Over time, enough rock is dissolved to create caverns and cave systems — a classic exam example of chemical weathering in action.

A fast-moving river carries sand, gravel, and silt. As it reaches a flat plain, its speed decreases. In what order are the sediments deposited, and what landform might develop at the river's mouth?

As the river slows, it loses energy and can no longer carry all its sediment load. Gravel (largest, heaviest) is deposited first, then sand, and finally silt is carried the farthest before settling. At the river's mouth where it meets a standing body of water and slows dramatically, the accumulated silt and sand build up into a delta — a classic deposition landform tested on exams.