Granite is the ultimate silicate rock. As discussed elsewhere in greater detail, on average oxygen and silicon account for 75% of the earth’s crust. The remaining 25% is split among several other elements, with aluminum and potassium contributing the most to the formation of the continental granitic rocks.

Three agents of physical weathering that can cause abrasion are moving water, wind and gravity. Also Rocks suspended in the ice of a glacier can cause abrasion of other rock on earths surface. And moving water rocks can become rounded and smooth.

Different rocks have different characteristics because of their minerals, the ways in which the rocks were formed, and the processes that acted on the rocks since they were formed.

The most important reason why we care about the strength of a rock is that when a large rock breaks, it can be a hazard and possibly cause a disaster. There are many different disasters caused by breaking rocks, including earthquakes, tsunamis, volcanoes, rock falls, and landslides.

Geologists study rocks because they contain clues about what the Earth was like in the past. We can assemble a historical record of a planet and trace events that occurred long before humans roamed our planet.

Sedimentary rocks tell us about past environments at Earth’s surface. Because of this, they are the primary story-tellers of past climate, life, and major events at Earth’s surface. Each type of environment has particular processes that occur in it that cause a particular type of sediment to be deposited there.

Igneous rocks

There are three kinds of rock: igneous, sedimentary, and metamorphic. Igneous rocks form when molten rock (magma or lava) cools and solidifies. Sedimentary rocks originate when particles settle out of water or air, or by precipitation of minerals from water. They accumulate in layers.

Answer: Serpentine minerals are made of tiny sheets of silica tetrahedrons that are loosely held together.

Diamond is the hardest known mineral, Mohs’ 10.

Talc

Limestone

Chalk is a sedimentary rock because it is formed of compressed sediment. It is also permeable because water can pass through it. Because chalk is sedimentary and porous it can be easily eroded and weathered by wind, rain and waves which means the chalk cliffs are often unstable.

Because the soft rock is exposed, it is eroded faster than the hard rock. This differential erosion creates headlands and bays along discordant coastlines. The soft rock is less resistant than the hard rock so it is eroded faster.

Metamorphic rocks are highly resistant to erosion and are often used in building materials.

Igneous rocks, especially intrusive igneous rocks such as granite, weather slowly because it is hard for water to penetrate them. Other types of rock, such as limestone, are easily weathered because they dissolve in weak acids.

Coastal erosion may be caused by hydraulic action, abrasion, impact and corrosion by wind and water, and other forces, natural or unnatural.