- Slides: 19
Sedimentary Rocks are #1 �Earth’s crust was made of IGNEOUS rocks �But 75% of the rocks on the Earth’s crust are SEDIMENTARY! �Why?
Sedimentary rocks are created from the EROSION and DEPOSITION of other rocks.
Formation of Sedimentary Rocks � 5 steps ◦ 1. Weathering – any process that breaks rocks into smaller pieces (sediment) ◦ 2. Erosion – the process of removing the sediments (wind, water, etc. ) ◦ 3. Deposition – the dropping of sediments ◦ 4. Compaction – squeezing layers of sediments together ◦ 5. Cementation – when dissolved minerals seep into the tiny spaces between the sediments, cementing them into a solid rock
Strata = Layering of Rock Youngest Layers Oldest Layers
Sedimentary Rocks are the ONLY rocks that contain FOSSILS!!
There are 3 main types of Sedimentary Rocks
1. Clastic Sedimentary Rocks �Rocks that break down under forces of nature - WIND and WATER!! �Made of pieces of other rocks
Examples of Clastic Sedimentary Rock �Conglomerate
Examples of Clastic Sedimentary Rock �Shale �Made up of clay sediments
2. Chemical Sedimentary Rocks �Water dissolves the minerals and they come out of the solution (precipitate) �The mineral crystals grow together to make the rock
Examples of Chemical Sedimentary Rock Salt (Halite) When water in ocean water evaporates, leaving salt crystals behind
Examples of Chemical Sedimentary Rock �Limestone ◦ MOST COMMON ◦ Found in caves ◦ Forms when calcium carbonate precipitates from a solution
3. Bioclastic Sedimentary Rock �Made of things that were once living ◦ Plant materials ◦ Shells
Examples of Bioclastic Sedimentary Rock �Coal – made of plant remains �Coquina – made of shells
Know how to read this for the TEST!!
Identify the bioclastic sedimentary rock with the varied grain size. Coal Identify the clastic sedimentary rock with the clay grain size. Shale Identify the crystalline sedimentary rock with halite composition. Rock Salt