Minerals, rocks, weathering, sequencing & energy Std. 3
Feb 22, 2016
Minerals, rocks, weathering,
sequencing & energy
Std. 3
Minerals• Must have the following 5
characteristics: – Naturally occurring– Inorganic – Solid– Crystal structure– Definite chemical composition
Identifying Minerals (physical properties)
• Color• Streak• Luster• Density• Hardness• Special Properties
Rock Cycle• Draw
igneous• Extrusive:– Surface– Cooled rapidly– Small crystals– Glassy
• Intrusive– Inside earth– Cooled slowly– Larger crystal
sedimentary• Clastic– Rock fragments– Conglomerate &
sandstone• Organic– Remains of plants &
animals– Coal & limestone
• Chemical– Minerals dissolved in
solution crystalize– Limestone, halite (rock
salt
metamorphic• Foliated– Grains in parallel
bands– Gneiss, slate
• Nonfoliated– No bands– Grains random
Weathering, erosion, deposition• Weathering– break rock down
• Erosion–move it
• Deposition– lay down sediment
EROSION• Water• Moves the most sediment
• Glaciers• U-shaped valley, till, moraines, kettle
lakes• Wind• Sand dunes
• Gravity• Move sediment downhill
• How fossils form– Death, soft parts decay, hard parts left
(teeth, bones)– Sediment covers organism– Sediment becomes rock, preserving parts of
organism
Types of fossils• Mold• Cast• Petrified– Cells replaced by minerals or sediment– Bones, petrified wood
• Carbon films• Trace fossil• Original/preserved remains– Ice, tar, amber
Fossils & the past• Where do fossils form?–Most: Organisms that once lived in or near
shallow water – Sedimentary rock
• Tell us about past environments– Shallow bay, ocean bottom, freshwater
swamp
Relative Age• Age comparison (older vs. younger)• Law of Superposition– Oldest layers at the bottom, youngest at
the top
Determining Relative Age• Extrusion, Intrusion, Fault,
Unconformity, Index fossil
- The Relative Age of Rocks
Energy transfer• Volcanoes– Heat and mechanical energy as magma
flows• Earthquakes– Energy transferred in seismic waves–Mechanical slipping of fault