622 INDEX TO THE STEATIGRAPHY OF NOETH AMEEICA. 



the Little Belt Mountains.- In previous investigations in this field by Weed and others the 

 Morrison formation has not been recognized, and the beds comprising it have been grouped 

 with the Kootenai and included in the "Cascade" formation. During the last field season 

 dinosaur bones provisionally regarded by C. W. Gilmore as of Jurassic age were found at one 

 horizon in many different localities; and at one exposure in sec. 3, T. 16 N., E. 2 E., about 30 

 feet below the bone-bearing bed, a green shale containing a distinctly fresh- water fauna later than 

 the Ellis formation was seen. These rocks, here provisionally regarded as constituting the 

 Morrison formation, consist of sandstone and bright-colored sandy shale with scattered layers 

 of impure limestone, many of them in lenticular form. The formation lies with apparent con- 

 formity on the EUis and is overlain conformably by the Kootenai. The thickness ranges from 

 60 to 120 feet, but the exact limits of the formation are in many places difiicult to determine. 

 Fragments of bone have been found at different horizons throughout the overlying Kootenai 

 formation, but thus far none that are sufficiently well preserved for specific determination 

 have been discovered in this region. It is possible that future investigation may prove that the 

 rocks here tentatively regarded as belonging to the Morrison constitute in reality a basal member 

 of the Kootenai. 



Section of supposed Morrison formation on the north side of Smith River, Montana. 



Kootenai formation. 



Morrison formation: Feet. 



Shale, soft, sandy 52 



Limestone, light-colored, nodular 4 



Shale, variegated , 33 



Sandstone, gray, massive 11 



Shale, greenish gray, sandy ,. 20 



Ellis formation. 



120 



Fisher gives other sections of the supposed Morrison and states that the rocks 

 have yielded invertebrate fossils which Stanton regards as "a fresh-water fauna 

 later than the EUis and suggestive of the Morrison." 



In regard to the character and extent of the Kootenai, Fisher has the following 

 to say : 



The Kootenai, as determined by the present investigation, comprises the upper one-third 

 of the Cascade and Dakota and the basal red shale included in the Colorado shale, as described 

 by Weed in the Fort Benton foho. * * * 



[This formation] consists of alternating layers of sandstone and shale, with the former 

 predominating, especially ia the lower half. The sandstones range in thickness from 10 to 60 

 feet and are more or less naassive in character. In the upper part shales are more abundant 

 and are interbedded with thin layers of impure sandstone. At Belt, on the east side of Belt 

 Creek, where a complete section was measured, the basal member of the formation consists of 

 a sandy shale interbedded with sandstone, the latter predominating, the whole having a thickness 

 of about 60 feet. This member consists locally of firm, massive sandstone with only a small 

 percentage of shale. It is overlain by coal, which here has a thickness of 6 feet, including 

 a few thin partings. Above the coal there is a dark coaly shale 5 to 6 feet thick, covered by 38 

 feet of massive light-gray sandstone. This sandstone is overlain by 138 feet of beds, consisting 

 in ascending order mainly of alternating layers of sandstone, red shale, and clay, with an 

 occasional limestone lens in the lower part. Above this alternating series there is about 200 

 feet of red shale, which constitutes the topmost member of the formation. The total thickness 

 is about 450 feet, which may be regarded as representative of the Kootenai formation as exposed 

 along the Belt Creek valley. * * * 



During the present investigation a number of detailed sections measured along Belt Creek 

 proved conclusively that the stratigraphic interval between the base of the Ellis and the 



