Weathering is the process in which rocks and minerals on Earth's surface are broken down by natural agents. These natural agents include water, ice, acids, salt, plants, animas, and temperature. Weathering can smooth and wear away rock. There is no rock that is hard enough not to be weathered.
There are two types of weathering: mechanical and chemical. Mechanical weathering, also called physical weathering causes rocks to crumble or disintegrate. One example of mechanical weathering is when water gets in cracks of rocks. This water could freeze and expand, widening the cracks and breaking the rock. Another example is when the temperature contracts and expands the rock. This can weaken the rock and cause it to break. Salt also weathers rock. It can get in cracks or pores of rock. Salt crystals can be left behind when saltwater evaporates, leaving behind some salt crystals. These crystals can grow, which puts pressure on the rock and breaks it. A seed can sprout in a rock, making cracks. Animals can break rock by digging and walking on the ground.
Chemical weathering changes the materials in soil or rock. One example is when carbonic acid, which is made when carbon dioxide mixes with water, dissolves rock. This is especially effective when dissolving limestone. Another example is when a rock with iron rusts and expands, which breaks the rock. Chemical weathering can cause holes, sinkholes, and caves to form in rocks.
Weathering is natural, but things humans do can speed it up or slow it down. Air pollution increases the amount of weathering, as does acid rain. Both of these are caused by human actions. Air pollution can be caused by burning things that can release certain chemicals. These chemicals can cause acid rain. The acid rain can weather rocks and gravestones.
There is no rock that is strong enough not to be weathered. Weathering is an essential process for soil formation. The broken up pieces of rock and minerals can mix with other materials to make soil. The broken up rock can be carried to the place they are to be deposited with a process called erosion.
Erosion is the process, normally occuring after weathering, in which earth is worn away by natural things such as wind, water, or ice. Erosion moves fragments of rock from place to place. Water, wind, and ice move rock fragments in very different ways.
One way water erodes is when rain can carry and wash away soil and fragments of rock. If water is muddy or dark colored, it can be a sign of erosion. Flowing streams or rivers can erode their banks, creating valleys. Water, especially waves, can carry sand from beaches, which moves the coastline inland. Crashing waves can change the shape of the coastline. They can make rocks into pebbles and change pebbles into sand. Waves can also make caves. If another wave crashes into the back of the cave, an arch can be formed. The top of the arch can collapse, making rock columns.
Wind can erode by carrying dust, sand, and...