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• deposits which in turn discharge to the surface water system. Therefore, <br />extensive groundwater investigations were not considered necessary or <br />appropriate in the loadout area. <br />Identification of Groundwater Aquifers. The Southfield Mine area lies on <br />the northeast flank of the Wet Mountains near the upper end of a closed <br />elliptical synclinal basin as illustrated by the Regional Hydrogeologic <br />Map, (Map 5). This basin was formed by folding associated with the Wet <br />Mountain uplift and is bordered by the Wet Mountain thrust fault which <br />forms the southern and western boundaries of the basin. The Chandler <br />Syncline, an asymmetrical structure with a steeply inclined western limb <br />and a gradual eastern limb, parallels the fault trace forming the axis of <br />the synclinal basin. The high point of the basin is just south of the <br />permit area along the Wet Mountain fault while the low point is the <br />Arkansas River to the north. <br />• Major stratigraphic units in this area including surficial <br />colluvial/alluvial deposits and the Poison Canyon, Raton, Vermejo, and <br />Trinidad formations, all produce water ,to some wells within the <br />groundwater basin. However, all are considered poor to moderate aquifers <br />generally yielding less than ten (10) gallons per minute to stock or <br />domestic wells. Groundwater yields are limited by the semi-arid climate <br />of the region, but more significantly by lack of lateral continuity within <br />the stratigraphic units. <br />The Vermejo formation which contains the coal seams being mined by the <br />Southfield operation is approximately 900 feet thick. Lithology of the <br />Vermejo formation is highly variable with significant cross-bedding and <br />inter-bedding, and lithotypes varying from well cemented sandstones to <br />fine grained indurated siltstones. While many of the sandstones and coal <br />seams within the Vermejo formation are capable of storing and transmitting <br />groundwater, the lenticular nature and significant cross-bedding and <br />inter-bedding which characterize this formation effectively limit lateral <br />• continuity and consequent groundwater transmission capabilities. Mann <br />(1957) summarized his observations "All of the Vermejo beds are <br />lenticular. Only a few coal and sandstone layers can be traced laterally <br />2.04.7-2 <br />