Rocks and the Rock Cycle Earth Science – Competency Goal 1.02

Rocks and Rock Cycle – Three Major Types Three major Rock types. Igneous Sedimentary Metamorphic

Rocks and Rock Cycle – Igneous Igneous – Latin Term – “From Fire” Igneous rocks form when magma cools and hardens. Magma is called lava if it cools at the Earth’s Surface 2 major types Igneous Intrusive – Magma forms and intrudes rocks beneath the Earths surface Extrusive – The rapid cooling of magma at the Earth’s Surface.

Rocks and Rock Cycle – Igneous Mineral Composition – Granite Family (Felsic) Rich in silica. Basalt Family (Mafic) Rich in iron. Texture – Extrusive Fine grained minerals – cool quickly, Pumice No mineral composition - Obsidian Texture - Intrusive Large minerals – cools slowly beneath the Earth and then more rapidly as it nears the surface – Granite. Page 178

Rocks and Rock Cycle – Sedimentary Sedimentary – Compaction and cementation are the process behind the formation of this rock type. Clastic – separate fragments of rocks are compacted to form one. Chemical – forms from minerals that have dissolved in water over time Organic – forms from the remains organisms- limestones, coal, fossils. Features – stratification, layering, ripple marks, mud cracks, salt casts.

Rocks and Rock Cycle – Metamorphic Rocks deformed from heat, pressure, and hot fluids can certain minerals to change into other chemicals. Types of Metamorphic Rocks. Unfoliated rocks no banding Foliated Rocks formed with a banding look – alternating dark and light bands. Extreme pressure will flatten them Different density will sort minerals