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<br />. <br /> <br />. <br /> <br />0:1494 <br /> <br />2. GeoloRic Data. <br /> <br />a. Strati~raphy. The age of deposition of bedrock and <br /> <br />unconaolidated material within the project area ranges from the Upper <br /> <br />Cretaceous time period of Recent. From youngest to oldest, the <br /> <br />vertical position and time relationships between layered rocks and <br /> <br />other deposits are as follows: <br /> <br />Time Period <br /> <br />Approx. Number of Years <br />Since Time Period Began <br /> <br />Recent <br />Quaternary <br />Tertiary (ear ly? <br />to late?) <br />Tertiary (Paleocene <br />or early) <br />La te Cre taceous <br /> <br />10,000 - 15,000 <br />1,000,000 <br />Indeterminate (prob. bet. <br />11 mil. to 40 mil. yrs.) <br />70,000,000 <br /> <br />100,000,000 <br /> <br />Formation Name <br /> <br />None (Valley fill) <br />None (Terrace Grave Is) <br />Igneous rocks (Basalt <br />dikes and sills) <br />Raton (upper) <br />{Raton (lower) <br />Ve rmej 0 <br />Trinidad Sandstone <br />Pierre Shale <br /> <br />Recent and Quaternary deposits form the valley floor and terraces <br /> <br />of the Purgatoire Valley. The material is composed of variable amounts <br /> <br />of clay, silt, sand, and gravel, occasionally segregated but usually <br /> <br />intermixed with two or more types, all of which have been transported <br /> <br />into the area from the Sangre de Cristo Mountains west of the project. <br /> <br />Igneous dikes and sills associated with the regional volcanic <br /> <br />activity of the Tertiary period intrude the Vermejo and Raton forma- <br /> <br />tions. These igneous rocks are fine grained, dark in color, and are <br /> <br />generally classified as basalt. Adjacent sedimentary rocks are <br /> <br />usually baked for a short distance from the contact. <br /> <br />The youngeat layered rocks exposed within the project area are <br /> <br />the lower strata of the Raton formation. Upper strata of the formation <br /> <br />are present beyond the limits of the project. Rock types within the <br /> <br />II -15 <br />