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uplifts of the adjacent highlands. Although there are no <br />• significant faults or folds mapped in the area, the coal seam <br />does "roll" or exhibit some minor structure. Most of this type <br />of structure is related to differential compaction within coal <br />seams, channel sands, etc. within the formation. <br />With regard to the regional stratigraphy the rocks outcropping in <br />the Northfork Valley would include from youngest to oldest the <br />Oligicene Intrusives, Ohio Creek Conglomerate, Mesa Verde <br />Formation, and Mancos Shale. In general, the Ohio Creek <br />Conglomerate and the Oligicene Intrusives will be found <br />topographically above the site toward McClure Pass. The Mancos <br />Shale outcrops downstream of the site toward Delta, Colorado. <br />• The most commonly used terminology for the Mesa Verde Formation <br />in the Northfolk Valley breaks the Mesa Verde into four members. <br />The base of the Mesa Verde is a thick, massive sandstone known as <br />the Rollins Sandstone Member. Immediately above the Rollins is <br />the Lower Coal Member, which commonly contains the A, Band C <br />seam coals. Above that unit is the Upper Coal Member which <br />contains the D, E and F seams. Although coal is present, no <br />significant minable seams are considered to exist above the F <br />seam. That portion of the Mesa Verde located above the F seam is <br />commonly referred to as the Barren Member. <br />L <br />6 <br />