Student Concept Map

Sedimentary Rocks Dr. David Steer

Rock Cycle

Group discussion time  Given:  Bag of sedimentary rocks Group these rocks in some manner.

Grouping items  Remember this exercise?

Grouping items  Group these objects in some logical way.

Grouping items  Group these objects in some logical way. Hit with a stick Use only hands Kick Throw Target Depositional setting (3) Texture

Sedimentary Rocks: Deposition  Clastic (detrital) sedimentary rocks –  composed of sediments, rock and mineral fragments formed when rocks disintegrate at or near the earth's surface.  Chemical sedimentary rocks  precipitated from a solution (e.g. sea-water) as the result of changing physical conditions (e.g. evaporation).  Biochemical sedimentary rocks –  formed by the actions of living organisms or composed of the remains of dead organisms.

Clastic or Detrital Sedimentary Rocks  Clastic sediments Classified based on:  coarse grain size particles  (gravel, includes pebbles, cobbles and boulders),  medium grain size  (sand)  fine grain size  (silt) gritty feel of sample  very fine sediment  (clay) too fine to see May appear layered

Clastic Rocks Classified SedimentGrain Size (diameter) Sedimentary Rocks Clay less than mm Shale, Mudstone Silt to mm Siltstone Sand to 2 mm Sandstone Gravel more than 2 mm Conglomerate

Review  Which rock is most likely sedimentary? Temperature when formed A B C D E Depth

Examples of clastic sedimentary rocks  Mudstone  Fine grained low energy  Sandstone  Medium grained moderate energy  Individual grains visible in samples  Conglomerate  Medium to coarse grained high energy

Chemical Sedimentary Rocks  Chemical sedimentary rocks –  precipitated from a solution (e.g. sea-water) as a result of changing physical conditions (e.g. evaporation).  May be difficult to see layers  Biochemical sedimentary rocks –  formed by the actions of living organisms or composed of the remains of dead organisms.  Fossils usually apparent

Examples of Biochemical Sedimentary Rocks  Limestones  form when marine organisms die and their skeletons accumulate.  Coal  forms when land plants die and their organic tissue accumulate.

Concept Map  Construct a concept map that guides you through classifying a sedimentary rock. Classify these rocks.