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1950 BUREAU OF MINES REPORT Mine workinos, p. 4. Mine workings in the central part of the Aspen district are continuous and interconnected for over 16,000 ft. from Aspen mountain northeastward under the Roaring Fork River to Smuggler mountain, and extend from 1,200 ft. below the valley surface to 800 ft. vertically above it.Z' All workings below the Cowenhoven and Lower Durant tunnel levels are flooded. when last worked in 1918, the workings below water level were kept clear by pumping through three shafts at a rate of 3,250 gallons per minute. The Deposits, pp. 4-10. Geologic features of Aspen district are not readily observable, as the surface is for the most part covered with glacial debris, alluvium and colluvium, and most mine workings are now inaccessible. volin and Hild's descriptions are a synthesis of Spurr, Vanderwilt, Rohlfing (largely unpublished), and others. Rocks in the district range from Precambrian granites and metamorphics through Paleozoic and late Mesozoic sediments. The Mesozoic sediments and the Precambrian basement are not important to the district ore deposits. Cambrian, Ordovician, Devonian, Mississippian, and Pennsylvanian rocks are present in Smuggler mountain, while only Devonian, Mississippian, and Pennsylvanian sediments are exposed in the accessible portions of the Smuggler mine. Granite (Precambrian). The Precambrian granite is commonly a coarse, granular rock, light green when fresh, reddish-brown when weathered. Principal minerals are pale-blue quartz, yellow to pink feldspar, and brown to dark-green mica. It is metamorphosed to gneiss or schist in some areas. Sawatch Ouartzite (Cambrian). The Sawatch lies [unconformably] on the [Precambrian] granite, with a thin bed of conglomerate at the base. The lower part is arkose or "granitic grit" grading upward to fine white quartzite, then into dolomite sandstone. The uppermost part, the Peerless Shale member, consists of massive, siliceous, shaly dolomites.70 Manitou Dolomite (Ordovician). The Manitou is entirely This does not agree with other descriptions (for example, SeuRR MONOGRAPH 226), or with the Aspen 7.5-minute quadrangle map, which describe and show mine workings at Tourtellotte Park, reported as continuous with others (Stefan Albouy, personal communication} at a maximum elevation of 10,800 ft., or 2,800 ft. above the valley floor, to a minimum of slightly over 6,500 ft. at the 18th level of the Smuggler, for a total vertical distance of nearly 4,500 ft. '0 The Peerless is now considered a separate formation, with the uppermost portion lower Ordovician in age. Bruce A. Collins - 19 - BIHLIOGRAPRY