of the Bear River Formation. 105 



in the coal-bearing Cretaceous sandstones near the east end of 

 Meek's section, which are now known to belong to the Colorado 

 formation.* 



Two miles north of Sulphur creek another small stream, 

 Stowe creek, has cut a deep valley across the upturned strata 

 showing good exposures of most of them. The following 

 detailed description will show that it supplements the Sulphur 

 creek section, especially in the western half. The strata are 

 all slightly overturned, dipping 75° to 85° east. The beds are 

 numbered from east to west. (See section 2.) 



Section on Stowe Creek. 



1. Bear River Formation. 



Obscure exposures of dark shales with calcareous bands 

 containing Pyrgullfera humerosa, Corbula pirifor- 

 mis, Goniobasis chrysalis, etc. 



2. Covered space about 500 ft. 



3. Jurassic? 



Reddish shales and shaly sandstones. Dip 85° east 100 ft. 



Light bluish shales with some sandstones near base 120 ft. 



Reddish shaly sandstone 200 ft. 



Shales and gray sandstones not well exposed 100 ft. 



Total 520 ft. 



4. Dakota? 



Brown conglomerate of small pebbles. Dip 85° east.. 150 ft. 



Covered in a valley 250 ft. 



Brown sandstone . 15 ft. 



Reddish and bluish soft shales with some thin bands of 



sandstone mostly covered 350 ft. 



Brown sandstone.. 20 ft. 



Variegated shales with thin beds of sandstone 425 ft. 



Coarse gray sandstone . 200 ft. 



Bluish and reddish shales 100 ft. 



* The reference of all the coal-bearing Cretaceous sandstones of this neighbor- 

 hood to the Colorado formation requires a word of explanation. There has been 

 much discussion concerning the age of these beds and their equivalents at Coal- 

 ville, Utah A number of invertebrate species have been described from them, 

 none of which excepting Inoceramus problematicus was known to occur in any of 

 the members of the Meek and Hayden section east of the mountains. Lithologi- 

 cally they have some resemblance to the Montana (Fox Hills) formation, and they 

 are underlain by beds of dark shales of the Colorado. For these reasons they have 

 been most frequently referred to the Fox Hills, now called the Montana formation. 

 My field work during the last two seasons has shown (I) that a large number of 

 the species of this peculiar fauna occur in the Colorado formation, east of the moun- 

 tains in southern Colorado, associated with the characteristic species of that forma- 

 tion; (2) that some of these characteristic species also occur in the Coalville beds. 

 We must therefore conclude that the Colorado formation attained an unusual thick- 

 ness along this western coast of the interior Cretaceous sea and that the local 

 peculiarities of its fauna as well as the greater thickness and coarseness of the 

 sediments are due to the proximity of the shore. These facts will be fully demon- 

 strated in a paper now in preparation and they are mentioned here only because 

 they have an important bearing on the age of the Bear River formation. 



