 | "Lulu, I've got a question! You've told me that rocks are mixtures of minerals and other things that have become attached to each other!! And I believe you!" |
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 | "That's good of you, Lou!" |
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| And you've told me about rocks that form as minerals grow and interlock! And about rocks that form as sediment grains become cemented together!" |
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| "I have indeed!" |
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| "And you've classified rocks on the basis of their origin as igneous, sedimentary and metamorphic!" |
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| "I plead guilty!" |
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| "But I have a question!!?!" |
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| "What's that, Lou!?" |
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| "If you hand me a rock, how can I tell how it formed?!!" |
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| "Lou, I've been waiting for you to ask....!" |
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| "I mean, if I see a rock where the grains are locked in place by material deposited between the grains, I know it was sediment that has been turned into rock by cementation! But if I see a rock with grains that all interlock, it could have formed from the cooling of a magma, from the evaporation of a salt lake, or through applying heat and pressure to a rock that already existed previously! How can I tell what went on?!!"" |
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| "Neat statement of the problem, Lou!" |
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| "There are four ways to tackle the problem. If one way doesn't work alone, try it in conjunction with one or more of the others!"- Look at the mineralogy of the rock: the minerals that the rock contains.
- Look at the 'texture' of the rock: the sizes, shapes and arrangement of the grains.
- Look at the 'structure' of the rock: larger scale features, such as layering or discontinuities.
- Look at field relationships: the size and shape of the rock body and how it relates to other rock bodies.
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| "That magic number 'four'! I hope the magic works! If it does...Oi, am I going to be an expert!! |
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