Physical Weathering - mainly occurs in deserts and high mountains

1. Change in temperature can break up rocks.  When rocks are subjected to continuous hot and cold spells, they expand and shrink.  Most rocks are made from mixtures of minerals.  These expand and shrink at different rates.  This causes stress to build up in rocks.  Eventually, they crack and crumble away. This is known as stratification.  To demonstrate this effect, we can heat a glass rod and drop it into cold water.  See animation below.

2. In regions where the temperature drops below 0°C , ice can weather rock away

When it rains, water collects into the cracks in rocks.  If the temperature drops below freezing, it turns into ice and expands. The expansion effect of ice pushes the rocks apart.  This is repeated as water thaws and freezes.  Eventually the pieces of rock break off by fracturing or shattering and fall to the lowest point on the ground.  This process is called Freeze thaw.  The broken off pieces of rock are called Scree.