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Scientific Intelligence. 



Tongue rivers, we have no definite information. The traders say the 

 same kind of lignite beds seen along the Yellow-Stone, occur along the 

 banks of the former as much as one hundred and fifty miles above its 

 mouth. 



The foregoing hasty sketch is given more with a view of showing the 

 extent of the country occupied by this great Tertiary lignite formation, 

 than with?any hope of conveying a definite idea of its precise limits. If 

 it should prove to be only a part of the same extensive fresh water lig- 

 nite formation observed by Sir John Richardson on the Saskatchewan, of 

 which we have little doubt, then it is highly probable the lignite and 

 coal formations mentioned by Mr. Isbister as flanking the eastern slope of 

 the Rocky Mountains, in the form of a continuous belt from the Saskat- 

 chawan to the Arctic Ocean, belong to the same epoch. 



For the most part, these deposits in Nebraska consist of beds of gray, 

 yellowish, whitish, and blue sand, sandstone, clay, &c, with alternating 

 strata and clay. These beds of lignite often take fire spontaneously, from 

 heat generated in the decomposition of iron pyrites, and burn for many 

 years at a time, sending forth suffocating sulphurous vapors, and causing 

 such an intense degree of heat as to fuse the contiguous clay and sand 

 into masses presenting every degree of compactness, from that of obsidian 

 to light vesicular lava. In some of the argillaceous beds, great numbers 

 of beautiful fossil plants are found, a fine series of which was collected 

 and placed for investigation in the hands of Dr. J. S. Newberry, the well 

 known botanical palaeontologist of Cleveland, Ohio. The remains of Mol- 

 lusca collected from these formations, over a wide extent of country, pre- 

 sent a remarkable uniformity of character, and as may be seen by the 

 following paper, are all, excepting a few land shells, referable to genera 

 usually found in fresh and brackish waters. It is an interesting fact that 

 the most nearly allied living representatives of many of these species are 

 now found inhabiting the streams of South Africa, Asia, China, and Siam, 

 apparently indicating the existence of a tropical climate in these latitudes 

 at as late a period as the Tertiary epoch.* 



Although there can be no doubt that these deposits hold a rather low 

 position in the Tertiary System, we have as yet been able to arrive at no 

 very definite conclusions as to their exact synchronism with any particu- 

 lar minor subdivision of Tertiary, not having been able to identify any of 

 the Mollusca found in them with those of any well marked geological 

 horizon in other counties. Their general resemblance to the fossils of the 

 Woolwich and Reading series of English geologists, as well as to those 

 of the great Lignite formations of the southeast of France, would seem 

 to point to the lower Eocene as their position. Yet it may be possible 

 these resemblances have resulted from the action of precisely similar 

 causes at a somewhat later period. 



It is a little remarkable that these formations differ in many respects 

 from those of the White River basin lying so near on the south. In the 

 first place they generally contain more sand, are usually characterized by 

 beds of lignite, and as yet have furnished no remains of Mammalia ; 



* "We are under many obligations to Dr. Issac Lea, of Philadelphia, for the 

 privilege of comparing our fossil species with analogous forms in his magnificent 

 collection of recent shells. 



