Rocks and Rolls

Rocks Nearly all rocks are composed of one or more minerals Geologists classify rocks according to how they were formed –Sedimentary –Igneous –Metamorphic

Sedimentary Rocks Most abundant rock type on the Earth’s surface –Sits on top of Igneous and Metamorphic rock Example: Hardboiled Egg –Sedimentary is the shell – Igneous and Metamorphic the egg Usually deposited in layers Three types / textures: –Based on where and how they were formed

ESRT – pg 7

Fossils

Texture 1- Clastic Inorganic – Land Derived Most common type of sedimentary rock Formed on land…from non-living sediments Formed from sediment (clasts) that are compacted- then cemented together –Based on the size of the grains they contain See ESRT Boulders Pebbles Cobbles

ESRT – pg 6

ESRT – pg 7

Compaction and Cementation of Clastic Sedimentary Rocks Sediments are deposited Sediments are cemented together by minerals Sediments are compacted ‘squished together’

Conglomerates All size sediments (rounded) Fragments deposited by a glacier as it melted –Compacted and Cemented together

Breccia All size sediments (angular edges) Fragments deposited –Compacted and Cemented together

SANDSTONE SHALE SILTSTONE

ESRT – Pg 2

Minerals are dissolved in water Water evaporates Solid mineral left behind (evaporite) Ex) salt water – when water evaporates…salt left behind….’Halite’ Texture 2- Crystalline Chemically and /or organically formed HALITE DOLOSTONE

Texture 3 – Crystalline / Bioclastic Formed from plant and animal remains –Coal FOSSILSOften FOSSILS found in Bioclastic rocks! COAL

COAL

Fossils

Environment of Formation Fossils, mud cracks and ripple marks –Help to identify where rock was formed

To help you remember