362 W. T. LEE UNCONFORMITY IN THE SO-CALLED LARAMIE 



the Cretaceous coal measures would be expected, yet the observed differ- 

 ence is 475 feet, the entire formation disappearing within a distance of 

 15 miles from the point of its maximum thickness. 



The contact between the Cretaceous coal measures and the conglom- 

 erate at the base of the post-Laramie is traceable in the face of the cliffs 

 as an unmistakable line of unconformity by erosion. Near the Van 

 Houten mine the conglomerate rests on 13 feet of coal and in a number 

 of places within the mine conglomeratic material fills irregular cavities in 

 the coal bed. Apparently these masses are due to the filling from above 

 of fissures and irregular openings formed at about the time the conglom- 

 erate was deposited. A quarter of a mile south of Van Houten this coal 

 bed and 40 feet of underlying sandstone and shale are absent and the 

 conglomerate rests on the Trinidad sandstone ; also differences in the de- 

 gree of dip between the Cretaceous and the post-Laramie coal measures 

 were noted in a few places where for short distances the conglomerate 

 extends across the eroded edges of the older beds, as shown in figure A, 

 plate 28. 



The following is a description of the sections represented on plate 28 : 



A is a section of Cottonwood canyon near Red River peak. The bedding planes 

 of the lower formation dip 3 degrees ; those of the upper are horizontal. 



B is a series of columnar sections extending from the base of the Rocky moun- 

 tains eastward to Van Houten. 



(1) Section in hogback 5 miles south of the Colorado-New Mexico 



boundary. 



(2) Section near the southeastern extremity of Vermejo park. 



(3) Section in Vermejo canyon east of Vermejo park. 



(4 and 5) Sections at eastern margin of field south of Van Houten. 

 C represents a series of columnar sections from near Carresso creek (6) north- 

 ward along the eastern nrnrgin of the field. 



(6) Cliff south of Carresso creek. 



(7) Dawson, west side of Vermejo canyon. 



(8) Four miles east of Dawson. 



(9) Half mile north of Koehler. 



(10) Three miles east of Koehler. 



(11) Two miles southeast of Van Houten. 



(12) Van Houten mine. 



(13) North fork of Willow creek, 1% miles north of Van Houten. 



(14) Two and a half miles west of Red River peak. 



(15) Red River peak. 



(16) One mile north of Red River peak. 



(17) North wall of Red River canyon. 



(18) Half mile south of Gardner. 



(19) One mile south of Raton. 



(20) Mesa north of Raton. 



(21) One and a half miles northeast of Raton. 



(22) Southeastern point of Bartlett mesa, 4 miles east of Raton. 



