W. Cross — Post-Laramie Deposits of Colorado. 21 



below any other recognized member of that division. Having 

 thus briefly restated the stratigraphical evidence of the forma- 

 tions near Denver the developments of the last three years in 

 other districts will be reviewed. 



Huerfano Series. — In the Huerfano basin in southern Col- 

 orado Mr. P. C. Hills has discovered and described * a series 

 of strata 7,100 feet in thickness which he refers to the Eocene, 

 because their lower member is decidedly unconformable with 

 the underlying well-known coal-bearing Laramie of southern 

 Colorado, and because the upper division contains mammalian 

 remains of the Bridger Eocene. For the whole series Mr. 

 Hills submits the following scheme of division : 



( Huerfano beds, 3,300 feet=Bridger Group. 

 Huerfano Series \ Cuchara beds, 300 feet ) T w 



(Eocene) ( Poison Canon beds, 3,500 feet C Lower Eocene - 



Great angular unconformity exists between the Laramie and 

 the Poison Canon beds, but none has been detected between 

 the designated members of the new series. The Poison Canon 

 and Cuchara beds are at present separated from each other and 

 from the Huerfano beds on lithological grounds only, the 

 former consisting of '' soft sandstones and fine conglomerates 

 of a yellowish tint, with occasional bands of yellow clay or 

 marl," while the latter is a well defined horizon of " pink and 

 white massive sandstones." The Huerfano beds consist of 

 " marls, clays, soft shales and sands, of red, gray, yellow, green 

 and purple colors, red predominating." In these have been 

 found remains of Tillot/ierium, Hyrachyus, Glyptosaurus, 

 JPalwosyops, and other forms which seem to correlate the 

 strata containing them with the Bridger Eocene. This dis- 

 covery of Eocene deposits, containing a well-marked mam- 

 malian fauna, on the eastern slope of the Rocky Mountains is 

 certainly significant. And it is highly probable, as pointed 

 out by Mr. Hills, that the Cuchara and Poison Canon beds are 

 contemporary with some of the other post-Laramie formations 

 to be mentioned. 



Gunnison County.- — A fund of new observations bearing 

 upon the present question is to be found in the address of Mr. 

 P. C. Hills as retiring President of the Colorado Scientific 

 Society, delivered December 15, 1890, but only very recently 

 published. f In that portion of this address treating of the 



* The recently discovered Tertiary beds of the Huerfano river basin, Colorado 

 (with map); Proc. Col. Scientific Society, vol. iii, part I, pp. 148-164, 1888. 



Additional notes on the Huerfano beds; ibid, vol. iii, part II. pp. 217-223, 1889. 



Remarks on the classification of the Huerfano Eocene. Read before the Col. 

 Sci. Soc , Feb. 2, 1891. Not yet published in full. 



•f Orographic and structural features of Rocky Mountain geology, Proc. Col. 

 Sci. Soc, vol. iii, part III, pp. 359-458. 1891. 



