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heated to boiling, and then treated with small quantities of sulphuric ted 
Geology. a 430 
de 
till there is no longer any increase of the precipitate formed. The cerium 
well as lanthanum, magnesium and cerium. ‘This liquid when evapora- 
ted yields a very beautiful double nitrate of lanthanum, didymium and 
Magnesium which forms the starting point of a series of double nitrates, 
II. GEOLOGY. 
1. Fossils of Nebraska, (1.) Letter from F. B. Meek and F. V. Haypew 
to G. K. Warren, Lieut. To og. Eng., dated Washington, February 8th, 
1858; printed in the National Intelligencer of March 16.—We have 
examined the fossils and other geological specimens collected under your 
direction during the past season in and near the Black Hills, Nebraska, 
and find that, in connexion with the facts noted, they indicate the follow- 
ing succession of geological formations in that region, viz. : 
irst. The main body or nucleus of the Black Hills is principally com- 
posed of a coarse feldspathic granite, which has been elevated by power- 
ful subterranean forces since the close of the Cretaceous Period, and pre- 
eae to the deposition of the Tertiary formations of the surrounding 
mili 
Y of the Silurian system. Amongst the specimen ; 
Tecognize Lingula, Obolus? and fragments of Trrilobites, belonging to spe- 
“es known to occur in the same formation in Wisconsin and Minnesota. 
A series of gray, reddish and whitish gritty limestones, sixty to 
3d. 
_ ne hundred feet in thickness, containing fossils which are clearly Carbon- 
