Lab: Formation Of Igneous Rocks (Page 3 of 3) in pdf

Lab: Formation Of Igneous Rocks Page 3

Post-‐lab q uestions:

1. Compare t he r ocks y ou m ade w ith t he f our i gneous r ocks i n y our b ox ( A-‐D). W hich

do y ou t hink c ooled s lowly? W hy? W hich d o y ou t hink c ooled q uickly? W hy?

2. Can y ou t hink o f a ny p lace o n e arth w here m agma p ushes t hrough t he c rust t o

become l ava a nd c ools q uickly? I f i t c ools q uickly, w ill y ou b e a ble t o s ee t he

minerals e asily?

The l ava t o m ake t hese r ocks e xtrudes f rom, o r c omes o ut o f, t he e arth. T hese r ocks a re

called e xtrusive a nd w ere f ormed o utside o f t he e arth’s c rust. T hey c ool q uickly a nd s o

have s mall m inerals t hat a re h ard t o s ee.

3. Which r ocks i n y our s et a re e xtrusive a nd c ame f rom v olcanoes?

Intrusive r ocks s tay i nside t he c rust u ntil t he r ock h as c ompletely c rystallized. W e h ave t o

wait m illions o f y ears u ntil t hese h uge p ockets o f r ock a re e xposed b y p late t ectonics a nd

erosion t o s ee t hem. T he m ountains a t Y osemite a re a ctually h uge p ockets o f i ntrusive r ock

that c ooled i nside t he e arth a nd w ere l ater e xposed.

4. Which o f y our r ocks a re i ntrusive r ocks?

SCWIBLES is an NSF-GK-12 project, #DGE-0947923,

Rock Types and Formation

a partnership between the University of California, Santa Cruz,

Igneous Lab

and the Pájaro Valley Unified School District.

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