EAS201 Lecture Notes - Lecture 11: Isocline, Mica, American Cordillera
20 Sep 2016
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We measure angle of dip, and if it"s going down 30 degrees that"s the dip. We use magnetic north, orient this dip relative to north. Strike: intersection of the plane of interest (line of intersection) Dip of 45 degrees north, strike is 90 degrees (goes from west to east) Strike of ~120/80 sw (right speaker in the room) Never have a strike more than 180 degrees. Because after 180 degrees it is the same orientation again. Think about arms outstretched showing the orientation (at 190 it just would be 10) Permanent strain: bend it to far, won"t go back to it"s original shape. Rock composition: quartz, olivine, garnet: brittle no cleavage=shatters mica, carbonates: ductile pronounces cleavage=act as glide planes, makes rock bend. [***^^^question on final exam, study this chart ^^^***] Right at the surface, just about all rocks seem brittle. Go down about 10 km, the rocks have confining pressure, they"re warmer, and in the brittle-ductile transition in crust:
