258 ANNUAL OF SCIENTIFIC DISCOVERY. 



forks of the Maramec, which is a tributary of the Missouri, there is- 

 sues from the limestone strata a river whose minimum delivery is 

 5,685 cubic feet per minute, furnishing sufficient water-power for 

 driving the forges, rolling-mill, furnace-blast, flour-mill, and saw-mill 

 of the Maramec Company. The water maintains a nearly uniform 

 temperature in summer and winter, but the quantity delivered varies 

 greatly. 



FALLS OF NIAGARA. 



PIJOF. AGASSIZ, in the early part of his new work on Lake Superior, 

 i_; led to speak of the falls of Niagara; and after saying that for ages, 

 while the falls have been receding from Lake Ontario, there has been 

 a layer of very hard rock at the surface, below which the softer rock 

 has crumbled away, causing the remarkable overhanging at Table 

 Rock and other localities, continues, " But from the inclination of the 

 strata this will not always be the case. A time will come when the 

 rock below will also be hard. Then probably the falls will be nearly 

 stationary, and may lose much of their beauty, from the wearing a\vay 

 of the edge rendering it an inclined plane. I do not think the waters 

 of Lake Erie will ever fall into Lake Ontario without any intermedi- 

 ate cascade. The Niagara shales are so extensive, that possibly at 

 some future time the river below the falls may be enlarged into a lake, 

 and thus the force of the falling w T ater diminished. But the whole 

 process is so slow that no accurate calculations can be made." 



ORIGIN OF SOME CURIOUS SPHEROIDAL STRUCTURES IN SEDI- 

 MENTARY ROCKS. 



AT the meeting of the American Association, at New Haven, Prof. 

 B. Silliman, Jr. exhibited some curious spheroidal structures, from 

 the rocks of the Niagara (N. Y.) group, well known to those con- 

 versant with the geology of that district. The specimens have a 

 curiously embossed and concave appearance, with the concavities 

 sometimes opposite to the convexities. The regularity of these im- 

 pressions is such, that, by taking any one as a centre, six others may 

 pretty generally be counted immediately around it. These appear- 

 ances have been figured by Mr. Hall, and the probable cause of the 

 phenomena has been the subject of no little speculation. Similar ap- 

 pearances, however, are produced at the present day by natural causes. 

 Prof. Silliman had observed, that excavations are made by tadpoles, 

 identical in appearance with those occurring in the old sedimentary 

 deposits of the rocks referred to. But there are no Batrachians so old 

 as the Niagara group, and therefore we are compelled to refer the 

 cause of the phenomena to the agency of great numbers of small gre- 

 garious fishes, and other animals, also gregarious, which are known 

 to have existed at that period. These views were corroborated by 

 Prof. Agassiz. 



