382 Miscellanies. 



impressions with which it is sometimes crowded, it marks out the ancient 

 coast line of a wide spread sea, beneath whose waters the vast extent of 

 sedimentary rocks stretching westward from the Blue Ridge were suc- 

 cessively deposited. The rock appears to have had a littoral origin, or at 

 least to have been deposited in shallow water and near the margin of the 

 sea. Throughout the whole of the vast area extending from the Blue 

 Ridge westward, the strata are for the most part of oceanic origin. The 

 ancient coast line has been traced out by Prof H. D. Rogers, in a vast 

 circuit north and west through Pennsylvania and New York, and even 

 into the valley of the Mississippi, along the region of the great lakes — 

 over which wide area similar geological laws prevailed — to an extent 

 without any known parallel — marine and littoral animals prevailing 

 throughout the whole of this region. The series of rocks is numbered 

 and described in detail in the reports. The limestone of the great val- 

 ley of Virginia affords numerous marbles — grey, white, red, and of many 

 colors. 



Near Wyer's cave a dyke of trap is found contiguous to the limestone, 

 and is the only mass of " igneous rock intruded among the limestones of 

 the valley ;" it is observed also that along the line of the canal near Har- 

 per's ferry the sandstones are vitrified by the subjacent igneous rocks, 

 while both they and the slates contain specks of epidote and chlorite, and 

 the lower beds have a jointed structure and confused stratification. It is 

 added, that in another place even the massive beds of hard sandstone 

 " display the marks of those violent agencies to which they owe their 

 present erect or inverted position, in countless intersecting joints and sur- 

 faces, polished by the attrition of rock grinding against rock, under the 

 most enormous pressure." 



Prof Rogers is happy in his descriptions, which are pictures to the 

 mind, and his style throughout is that of a scholar accustomed to good 

 writing. 



The rocks of Pennsylvania are in many respects very similar to those 

 of Virginia, but in the latter state there are vast deposits of the marine 

 tertiary which are absent from the former. We shall not attempt to give 

 the characters of the various formations which are described by Prof H. 

 D. Rogers in regular order from the primary rocks to those above the 

 coal formation. 



No portion of the United States is richer in valuable minerals than 

 Pennsylvania and Virginia. Coal, iron, lead, gold, limestone, gypsum, 

 and valuable saline and mineral waters are among their treasures, and the 

 marine tertiary affords to Virginia inexhaustible resources for agriculture. 

 Large portions of secon'dary rocks appear to have been swept away by 

 floods. 



The Potomac marble, used for columns in the capitol at Washington, is 

 member oftlie red sandstone formation; it extends into Pennsylvania and 

 New Jersey on the one hand and into Virginia on the other. It is aeon- 



