S.F.W.

Rocks

Rocks

Welcome to my sedimentary page!!

Sedimentary rocks are made up of sediments. Sediments are lots of small pieces from rocks, soil, parts of plants and animals. It can also be sand, mud, and pebbles. As time goes by, the layer of sediment on the bottom of lakes and most importantly on the bottom of the ocean will grow deeper and deeper soon going to the depths of thousands of feet. The weight and pressure of all the sediments, pushing on layers below them with tons of force. Numerous minerals that act like cement, pushes the sediment together and then cements together.They are types of rocks that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water. Sedimentary is the collective name for processes that cause mineral or other particles to settle in place. Sedimentary rocks cover up most of Earth's surface. Some other sedimenary rocks are limestone, sandstone, mudstone, greywacke, chalk, coal, claystone and flint.

Igneous Rocks

Igneous Rocks are formed through the cooling and solidification of magma or lava.It is also one of the three main rock types along with, sedimentary and metamorphic. They form as liquid magma cools, which forms crystal structured rocks. It can form with or without crystallization that is above, or below the surface. Usually igneous rocks that are formed deep within the Earth's surface where temperatures are very high take up to thousands of years to cool down. This makes the crystals much bigger, usually granite. Igneous rocks that form on Earth's surface cool in just afew hours. However, the crystals that are in the rock can be microscopically small. Scientists divide igneous rocks into two different categories. They are divided by which ones cool below the surface, and the ones that cool above the surface. The ones that start below the surface are called intrusive rocks and the ones that started above the surface are called extrusive rocks. Examples of intrusive igneous rocks ae diorite, gabbro, granite, pegmatite, and peridotite. Examples of extrusive igneous rocks are andesite, basalt, obsidian, pumice, rhyolite, scoria, and tuff.

Metamorphic Rocks

Metamorphic rocks are a type of rock that has been changed from extreme heat and pressure. This causes physical and/or chemical changes. They come from deep within the Earth when heat and pressure get applied to igneous and/or sedimentary rocks. The heat and pressure change the shape and their structure stability. The rocks get melted only a little and the chemicals that are in the rocks are rearranged so that the new rock is very different from the original rock. Another way to say this is that a metamorphic rock is a result of a transformation of a pre-existing rock. The original rock gets very high heat and pressure which causes physical and/or chemical changes. Some types of these rocks are marble, slate, gneiss, and schist. The final step of how a metamorphic rock forms is it depends on the amount of pressure that the rock got, the amount of heat the rock got, and the amount of time the rock got to pressure and heat. Marble is a very common metamorphic rock. Marble is formed when heat and pressure are applied ot limestone for many thousands of years.