USGS Visual Identifier

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Geologic Unit: Dyer 

Publication:
Behre, C.H., Jr., 1932, Weston Pass mining district, Lake and 
   Park Counties, Colorado: Colorado Scientific Society Proceedings, 
   v. 13, no. 3, p. 55-75.
Usage in Publication:
Dyer dolomite member*

Modifications: Geologic Province: Dominant Lithology:
 Named
  Eagle basin
South Park basin
  Limestone

Summary:
Named as upper member of Chaffee formation for typical exposures on West Dyer and Dyer Mountains, 5 mi east of Leadville, Lake Co, CO in Eagle basin and Park Co in South Park basin. No type locality designated. Composed of 75 ft of light-gray, sugary, dolomitic limestone, with a few dark-gray and ocher-colored beds. Was formerly included in the Leadville limestone (called "Blue" limestone by miners). Overlies Parting member of Chaffee; underlies Leadville. Is of Devonian age.
Source: GNU records (USGS DDS-6; Denver GNULEX). 


Publication:
Tweto, Ogden, 1949, Stratigraphy of the Pando area, Eagle County, 
   Colorado: Colorado Scientific Society Proceedings, v. 15, 
   no. 4, p. 149-235.
Usage in Publication:
Dyer dolomite member*

Modifications: Geologic Province: Dominant Lithology:
 Revised
Areal limits
Overview
  Eagle basin
  

Summary:
Recognized as the upper member of the Upper Devonian Chaffee formation in Pando area of Eagle basin. Overlies Parting quartzite member of Chaffee conformably. Is overlain disconformably by Gilman sandstone member (newly defined) of Leadville limestone. Is 80 ft thick over most of the area, but pre-Gilman channeling has modified the unit so that no more than 60 ft are present at some places along the Eagle River. One measured section described from exposures on east side of Eagle Canyon, 2.3 mi north of Pando.
Source: GNU records (USGS DDS-6; Denver GNULEX). 


Publication:
Campbell, J.A., 1970, Stratigraphy of Chaffee Group (Upper 
   Devonian), west-central Colorado: American Association of 
   Petroleum Geologists Bulletin, v. 54, no. 2, p. 313-325. 
   [Available online, with subscription, from AAPG archives:  
   http://www.aapg.org/datasystems or  http://
   search.datapages.com]
Usage in Publication:
Dyer Formation

Modifications: Geologic Province: Dominant Lithology:
 Revised
Redescribed
Overview
  Piceance basin
Greater Green River basin
Eagle basin
  Dolomite
Limestone

Summary:
Raised in rank and assigned as upper of two formations of Chaffee Group (rank raised). Divided into two newly named members (ascending): Broken Rib and Coffee Pot Members. Dyer occurs in Rio Blanco and Garfield Cos, Piceance basin; Routt Co, Greater Green River basin; and Eagle and Pitkin Cos, Eagle basin. Consists of dolomitic limestone (Broken Rib) and dolomite (Coffee Pot). Isopach maps of members show that Broken Rib ranges up to 80 ft thick in northwest part of study area and Coffee Pot ranges up to 120 ft thick in southwest part of area; members thin to east and northeast. Conformably overlies Parting Formation (rank raised); disconformably underlies Gilman Sandstone Member of Leadville Formation. Measured section; fence diagram. Assigned latest Late Devonian age though upper part of Coffee Pot may be Kinderhookian age.
Source: GNU records (USGS DDS-6; Denver GNULEX). 


Publication:
Sandberg, C.A., and Poole, F.G., 1977, Conodont biostratigraphy 
   and depositional complexes of Upper Devonian cratonic-platform 
   and continental-shelf rocks in the western United States, IN 
   Murphy, M.A., and others, eds., Proceedings of the 1977 annual 
   meeting of the Paleontological Society on Devonian of western 
   North America: University of California-Riverside, Campus 
   Museum Contributions, Paleontological Society, 1977 Annual 
   Meeting, Riverside, CA, November, 1977, no. 4, p. 144-182.
Usage in Publication:
Dyer Dolomite*

Modifications: Geologic Province: Dominant Lithology:
 Biostratigraphic dating
  Eagle basin
Piceance basin
  

Summary:
In a section on the Eagle-Garfield Co line just east of Glenwood Canyon, CO in the Eagle and Piceance basins, the Dyer is 46 m thick, lies above the Parting Formation, and below the Gilman Sandstone. The Coffee Pot Member at the base [should be top] is in the Polygnathoid-Pelekysgnathoid biofacies, or upper part of the Upper POLYGNATHUS STYRIACUS conodont zone. Broken Rib Member at the top [should be base] is in the Lower BISPATHODUS COSTATUS conodont zone and in an unzoned interval. At this locality, the Dyer is of Late Devonian, Famennian age. Lithofacies map.
Source: GNU records (USGS DDS-6; Denver GNULEX). 


Publication:
Tweto, Ogden, and Lovering, T.S., 1977, Geology of the Minturn 
   15-minute quadrangle, Eagle and Summit Counties, Colorado: 
   U.S. Geological Survey Professional Paper, 956, 96 p., (incl. 
   geologic map, scale 1:48,000)
Usage in Publication:
Dyer Dolomite*

Modifications: Geologic Province: Dominant Lithology:
 Overview
Age modified
Redescribed
  Eagle basin
  Dolomite

Summary:
Is middle of three formations of Chaffee Group (revised). Consists almost entirely of dolomite within Minturn quad, Eagle and Summit Cos, CO, Eagle basin. Dolomite is gray to black, much of it finely laminated in shades of gray, and is characteristically fine grained, thin-bedded, and breaks into small, sharp hackly fragments. Laminations are wavy and have been interpreted as stromatolitic in origin by Campbell (1970). Lower half to two-thirds weathers light buff or yellowish gray; upper part weathers dark brown to bluish gray. Within canyon of Eagle River and in adjoining mines, Dyer contains several distinctive marker beds. Except where channels have been cut into unit, Dyer is uniformly 75-80 ft thick in most of area near Gilman and southward to Leadville. Conformably overlies Parting Formation (redescribed) of Chaffee; unconformably underlies Gilman Sandstone (revised) of Chaffee. Measured section; geologic map; stratigraphic chart. Others have reported Upper Devonian brachiopods elsewhere in lower part of unit. Upper part of Dyer is poorly fossiliferous and its age is not well established. Other have reported fossil coral in upper part of Dyer suggesting Early Mississippian age; Dyer passes westward into Lower Mississippian limestones in subsurface; and Early Mississippian endothyrid Foraminifera occur in upper part of correlative Ouray Limestone. Based on the above, Dyer considered Late Devonian and Early Mississippian? age.
Source: GNU records (USGS DDS-6; Denver GNULEX).