328 GEOLOGICAL SUEVEY OF THE TEREITOKIES. 



time and experience than Ihad at my disposal. I shall therefore refer for 

 details to the reports already published,* and restrict my observations 

 to facts essentially connected with my line of researches — on the age of 

 this Lignitic formation as indicated by vegetable remains. 



Golden is on the banks of Clear Creek, at its outlet from a deep canon, 

 and in the middle of a narrow valley, shut up on the west by the slopes 

 of the primitive rocks and on the east by a high wall, a trap-dike, which 

 here follows the same trend as that of the mountain at a distance of one 

 to one and one-half mile. As it is generally the case along the eastern 

 base of the Eocky Mountains, the more recent formations have been 

 thrown up and forward, and their edges upraised to a certain degree 

 nearest to the uplift, and thus succeeding each other by hog-backs facing 

 the mountains, they pass toward the plains in diminished degrees of dip, 

 and soon take their original horizontal position. 



At Golden, the Lignitic strata, compressed, as they are, between two walls 

 of eruptive rocks, have been forced up on the western side in a nearly per- 

 pendicular position, while on the other they were thrown up at the same 

 time by the basaltic dike, and thus folded or doubled against their faces 

 in the same way as the measures of the anthracite basin of Pennsyl- 

 vania have been so often compressed in multiple folds between 

 the chains of the Alleghany Mountains. In that way the lowest strata 

 of the Lignitic, which are nearly perpendicular, overlie the Upper Cre- 

 taceous strata, which, following the slope of the mountain's plunge, in- 

 clined in a less degree. The line of superposition of both formations is 

 seen along a ditch opened for a canal of irrigation, about 200 feet from 

 the tunnels made in a bank of clay which underlies the lower lignite- 

 bed, and which is worked for pottery. These upper Cretaceous strata 

 ^ are seen in the same position, and exactly of the same nature as at 

 Gehrung's : thin beds of soapstone, or laminated clay, with Cretaceous 

 fossils, and above them the same kind of Tuten-clay, a few inches thick, 

 under the lower sandstone of the Lignitic, which is there covered. The 

 surface of the ridge formed by the upthrow is pierced by the edge of 

 the perpendicular strata, especially of the hard sandstone, and there 

 the characters of the lowest beds are recognized at many places as the 

 same as those of the fucoidal sandstone of the Eaton Mountains. At 

 the cut made across the measures by Clear Creek, the lower sandstone 

 appears proportionally thin, 10 to 20 feet. It is a white, soft-grained 

 sandstone, hardened by metamorphism, containing, besides remains of 

 decotyledonous leaves, some species of finely preserved fucoids ; among 

 them one species as yet undescribed and not seen elsewhere. In follow- 

 ing the same sandstone to the south it is seen increasing in thickness, 

 and near and under the Eoe coal, five miles from Golden, it forms a 

 high, isolated ridge, at least 200 feet thick, barren of any kind of re- 

 mains, except some fucoids. 



By its compound the alternanee of its coarse-grained and soft-grained 

 strata, these being often mere clay or mud beds, its characters appear 

 the same as those of the lower Lignitic sandstone of the Eaton Mount- 

 ains. It has, too, broken, undeterminable fragments of wood, cyperaceae, 

 &c. Besides the species of fossil decotyledonous leaves found in the white 

 sandstone of Golden, most of them homologous, or even identical with 

 some species of the Eaton and other localities, it has one of those very 

 rare land-plants which have been described and recognized in Europe 

 as pertaining as yet exclusively to the Eocene.t 



*Dr. F. V. Hayden, Silliman's Journal, March, 1868, pp. 101 ; Geological Report, 1869, 

 pp. 29 to 37 ; Notes on Geology, &c., by Dr. Leconte, pp. 47 to 53 ; on the Tertiary Coal 

 of the West, by James T. Hodge, in Hayden's Geological Report, 1870, pp. 318 to 329. 



+ See description of sx^ecies for further details. 



