Anonymous
Anonymous asked in Science & MathematicsEarth Sciences & Geology · 1 decade ago

What kind of rocks are the San Juan Mountains made of???

um.. it is a science project and i need info on what kind of rocks like basalt, obsidian, granite, etc...

when it was made like 120 million years ago or something like that

um.. San Juan Mountains in COLORADO!!!

NOT UTAH!!!!!!!!!!!!!!!

ok

so if any one kind find me an answer u are a savior

PLEASE help

thanks

~claire~!

1 Answer

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  • Anonymous
    1 decade ago
    Best Answer

    The San Juan are the grand range of eruptive mountains

    They run a whole gamut of volcanic and intrusive dike rocks

    Basalt, rhyolite, dacite, ash flow, air deposits, all extensively glaciated in grand fashion, often obscuring the local sedimentary and metamorphic rocks. The San Juans are the source of

    the Rio Grande and Arkansas Rivers as well as the Colorado.

    A good way to get in character of appreciating the San Juans is to read the Hayden survey of 1869.

    (Geological and Geographical Survey of the Territories (U.S.)

    [1st]-12th annual report of the United States Geological andgeographical survey of the territories... / By F. V. Hayden,United States geologist.

    Washington : Govt. print. off., 1867-83.

    Title varies: 3d (1869) Preliminary field report of the UnitedStates Geological survey of Colorado and New Mexico.--4th (1870)

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