The rock cycle is a process in which rocks are continuously transformed between the three rock types igneous, sedimentary and metamorphic. If the sediments are buried under further layers of sediment, they can become lithified to produce a sedimentary rock. Magma is produced when rocks are melted.

Cooling of the magma can occur beneath the surface (plutonic) or on the surface (volcanic). Igneous rocks can be identified by the determination of the composition and texture of the rock. Once these two characteristics have been identified, the Igneous Rock Identification chart is used to identify the rock name.

Steps in Identification:

1. Determine the color (indicates mineral composition)
2. Determine the texture (indicates cooling history)
3. Phaneritic = large grains.
4. Aphanitic = small grains (too small to identify with the naked eye)
5. Porphyritic = fine grains mixed with larger grains.
6. Vesicular = holes.
7. Glassy = glass-like.

Igneous rock is created by volcanic activity, forming from magma and lava as they cool and harden. It is most often black, gray, or white, and often has a baked appearance. Igneous rock may form crystalline structures as it cools, giving it a granular appearance; if no crystals form, the result will be natural glass.

Geologists like igneous textures because they reveal so much about how a rock formed. The first set of textures focuses on the size of mineral crystals. Crystal size primarily reflects the rate of cooling, but is also often strongly affected by rock composition (especially water or gas content).

Rocks are great at suffocating weeds and show a better success rate at weed-prevention than mulch. Stone cover is perfect for low-water gardens and landscapes. However, stones aren’t the perfect solution for gardens that may get a lot of sun because they can hold more heat than mulch.