308 



W. II. WEED — TWO MONTANA COAL FIELDS. 



9 J 



Red sands and gypsum layers made up as follows : 



_/'. Sands, red 10 



e. * rypsum, pure 5 



d. .Sands, green-gray, shaly 35 



c. ( rypsum, impure 11 



b. Sands, reddish, soft, '■'> belts of gypsum, 



3 to 6 inches 25 



a. Sands, crumbling, red and white or 

 gray 25 



Limestones, granular, earthy 



Sandy clays, red and green mottled. 



Feet. 



30 



1. Carboniferous limestones'"' 200 



2,572^ 



The Carboniferous. — The series of red sandy gypsiferous beds overlying 

 the massive limestones of the Carboniferous and so closely resembling 

 the " Triassic " red beds were diligently searched for any traces of fossil 

 remains, but without success. This series (number 2 of the section) con- 

 sists of crumbling sands, soft and often incoherent, generally red in color, 

 though also white and gray, containing numerous seams or beds of 

 gypsum. The series corresponds in position and general characters to 

 the "red beds" which overlie the Carboniferous in Wyoming. 



Overlying these gypsiferous red sands, there is commonly seen a series 

 of gray beds, also characterized in this section by layers of gypsum, one 

 of which is 3 feet in thickness. The gray shales and earthy limestones 

 of this series (number 3 of the tabular section) is capped by a belt of 

 black chert 8 feet thick, which was found at this horizon in several parts 

 of the field. The earthy limestones and shales resemble the Jurassic of 

 southern Montana, but are barren of fossils. 



The series of alternating red or purple and gray shales and limestones 

 (number 4 of the section) are characterized by abundant fossil remains. 

 The thin beds of limestone, often but a few inches in thickness, contain 

 a number of small serpulas and the shales contain a variety of fossils. 

 These fossils have been seen by Dr. C. A. White and unhesitatingly 

 referred to the Carboniferous age. They have been identified by Mr. C. D. 

 Walcott, who reports the following species, viz, Retzia verneuiliana, Hall : 

 Rhynchonell'a osagensis, Swallow; Alhyris subtilita, Hall; Bellerophon car- 

 bonariios, Cox ; also lamellibranch shells belonging to the genera AUorisma, 

 Schizodus, and Aviculopecten ; as well as two species of Fenestella, shown on 

 thin fragments, and two species of coral of the genera Chsetetes and 

 Lophophyllum ( .'). Mr. Walcott reports that " the species appear to have 

 lived in a sea not favorable to their full growth or development." 



The section made by Professor Davis a few miles farther eastward has 

 already been noted. I have examined the rocks at this locality and 



♦ Characteristic Carboniferous fossils were found in the uppermost strata of number 1, establish" 

 ing its age beyond anv doubt. 



