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KNOPF REPORT <br />found at the contact between the Leadville dolomite and the <br />overlying Weber [Belden] shaly limestone, and on Aspen <br />mountain between the dolomite and the overlying limestone, <br />both Leadville. The assumption has been that the ore found <br />along these contacts occurred as contact veins. As a result <br />the cross-faults, never regarded as ore channels, have never <br />been prospected, nor have other contacts. <br />According to the revised interpretation, the orebodies occur <br />at intersections of cross-faults and normal sedimentary <br />contacts. It is quite possible, therefore, that orebodies <br />may be present at the intersections of these faults with <br />other contacts both lower and higher. Vanderwilt suggests <br />the evaluation of the following horizons: (1) shaly beds of <br />the Sawatch Quartzite; (2) the Parting member of the <br />Chaffee; (3) the contact between the Leadville limestone <br />[Castle Butte] and the overlying weber [Belden} shaly <br />limestone; and (4) the contacts between the porphyry and the <br />Weber (Belden]. At least some mineralization has been <br />reported at all these horizons except the Sawatch shales. <br />Good ore has been found on Smuggler mountain where the <br />Parting [Formation) has been faulted against the dolomite- <br />shaly limestone contact [Red Cliff-Belden], although it was <br />apparently not recognized as Parting by the operators. <br />A. KNOPF, RECENT DEVELOPMENTS IN THE ASPEN DISTRICT, COLORADO, U.S. GEOLOGICAL <br />SURVEY BULLETIN 785-A (1926) . <br />Knopf 's report is essentially an extension of Spurr's work <br />to the south in the Richmond Hill area (Little Annie, <br />Midnight mine areas). Hut it does contain pertinent <br />comments concerning the glacial till covering of the <br />Smuggler mountain deposits, the supergene enrichment of ore <br />bodies in and adjacent to some of the glacial deposits, and <br />a more detailed description of intrusive rocks as related to <br />ore deposits throughout the district. <br />Glacial cover p. 3. Knopf discusses the lack of outcrops on <br />Smuggler mountain. <br />Cowenhoven tunnel p. 16. Knopf states that the Cowenhoven <br />tunnel was being reopened in 1923 by Silver Mines Co, of <br />America to provide access to old works in Smuggler mountain. <br />From the date it would appear this led to the work referred <br />to elsewhere as being performed by The Continental Divide <br />Development Co. (Part VII, post, pp. BO-89). <br />Hruce A. Collins - 16 - BIeLIOCRAPHY <br />