58 OAUHONII-KWOUS FORMATIONS AND FAUNAS OF ('OLOKAI)O. 



))y llio I'iuk Uiiiigc on Uic, cast, .soutli by tlic Etiglc and (Triuid rivcr.s, iiiid north by 

 tlio Boar Rivor. Westward the work extends nearly to longitude 108*-." Th(^ urea 

 tiuis bounded iiii hides within its limits tiie larger portion of the Grand liiver Cai'- 

 l)oniferous outcrop, and it is much to be regretted that owing to Marvine's untimely 

 death his geologic report never reached publication. There is very little literature 

 aside from this upon the geology of the Grand River area north of the line made 

 liy the Grand and Eagle rivers, and our information concerning it is almost restricted 

 to such facts as are deducible from the maps of the Hayden Atlas of Colorado," 

 together with the section (B, Sheet XVII), which passes just north of parallel 39° 

 46' north, and fi'om such inferences as ma}' be framed from consideration of the 

 geology of adjacent territory. From the maps and sections the Paleozoic rocks are 

 seen to consist of Silurian, Lower Carboniferous, Middle Carboniferous, and Upper 

 Carboniferous, the latter being followed by those of Triassic age. The character 

 and thickness of these formations can not be ascertained from this source. 



Peale in 1873 was assigned to the South Park district,'' which is defined as being- 

 limited on the north bj^ the parallel of latitude 39° 15', on the-south bj' parallel 38° 

 30', on the east by the eighth guide meridian of the land survey, and on the west by 

 the one hundred and seventh meridian. In 18Ti Peale surveyed the territory^ to the 

 north and west of this,' with the following boundaries: "Commencing at the inter- 

 section of meridian 109° 30' and the Grand River, the line runs northeastward up the 

 Grand River to the junction of the Eagle River; thence up .Eagle River to the 

 mouth of Roche Moutonnee Creek; thence westward along the northern boundary' 

 of last summer's (1873) work to its intersection with meridian 107°; thence south- 

 ward along the western side of last summer's work, approximately on the one 

 hundred and seventh meridian, to parallel 38° 30'; thence westward on this parallel 

 to the intersection of meridian 109° 30'; and thence northward on this meridian to 

 the intersection of 109° 30' with Grand River." This area not only adjoins his own 

 work on the north, as has already^ been set down, but it is conterminous also with 

 Marvine's district of the same year. 



During the operations of these two years Peale made several sections on Eagle 

 River, which it is of intei'est to compare with the sections of the Aspen and the Ten- 

 mile districts already considered. The most important of these sections appeared in 

 three different forms. It was originally^ published in the annual x-eport for 1873, 

 where it is incomjDlete. In the report for 1874 it is repeated, with some additions, 

 and in the report for 1875 it is summarized for comparison with other sections, 

 similarly prepared, of different areas surveyed by the same author. In each case 

 the series is subdivided, upon evidence more or less indifferent, into the great time 



II C. S. Geol. Geog. Surv. Terr. Geol. and Geog. Atlas of Colorado, etc., 1877. 

 b U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Kept,, for 1873, 1874, pp. 194-278. 

 c U. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Eept., for 1874, 1876, pp. 73-180. 



