330 ANNUAL OF SCIENTIFIC DISCOVERY. 



tinue in this rock. At certain points they occupy large fissures or caves 

 in the rock. The galena is in large crystals, clinging to the tops or sides, 

 and perfectly pxire never at the bottom, except as they are broken off 

 and mingled with pieces of broken rock. But when we pass deeper into 

 the Trenton limestone, the veins are oftener horizontal, spread in fiat, tliin 

 sheets. Here the lead is combined with the oxides and sulphates of iron 

 and zinc " blackjack " and " dry bones," the miners call it. Heretofore 

 the popular belief was, that the lead failed on striking this blue limestone ; 

 but at several points he found that, without being aware of it, the miners 

 had worked past even the limestone into the sandstone, and found rich 

 veins even there. These lateral veins of the blue (Trenton) limestone lie 

 parallel to each other ; they extend a great distance, and have been 

 worked for a mile. Prof. Daniels inclined to think that the deeper veins 

 will be found not inferior to those nearer the surface. He found occa- 

 sional veins of copper, but they were entirely independent of the lead 

 veins. The lead veins are in groups, and their lateral veins seem to con- 

 nect the larger vertical ones of the same group. 



Prof. Hall said, that in 1850 this galena limestone was first identi- 

 fied with the Lower Silurian rocks, and he thought the belts spoken of 

 were all of the same age. This region had never suffered from great press- 

 ure below, and he thought that the veins of lead had not been injected 

 into the fissures from below, but must have flowed in from above, while 

 in watery solution. The reason why the veins were horizontal in the blue 

 (Trenton) limestone, was because the fissures in the rock were lateral 

 not that the veins had been pressed together and thrown up laterally after 

 they were filled. The shale above the lead-bearing rock he supposed to 

 be of the Hudson River group. 



ON THE CONNECTION BETWEEN THE RED SANDSTONES OF THE 

 MIDDLE STATES AND CONNECTICUT VALLEY WITH THE COAL- 

 BEARING ROCKS OF EASTERN VIRGINIA AND NORTH CAROLINA. 



At a recent meeting of the Boston See. of Nat. History, Prof. "SV. B. 

 Rogers exhibited a series of fossils from the middle secondary belts of 

 North Carolina, Virginia, Pennsylvania and Massachusetts chiefly, ]\e 

 said, with the view of calling attention to the evidence afforded by some 

 of them of the close relation, in geological age, between what has been 

 called the New Red Sandstone of the Middle States and Connecticut valley, 

 first designated by Prof. H. D. Rogers as the middle secondary group, 

 and the coal-bearing rocks of Eastern A r irginia and North Carolina. 



Prof. R. referred to the existence in Virginia of three distinct belts of 

 these rocks. The most eastern of these, extending almost continuously 

 from the Appommatox River to the Potomac, includes the coal fields of 

 Chesterfield and Henrico counties. The middle tract, about 25 miles 

 west by south of the preceding, is of much less extent, and has not yet 

 furnished any workable coal seam. Somewhat intermediate in trend to 



