W. M. Fontaine—NMesozoie Strata of Virginia. 155 
series, The material of these beds comes from the decay of 
the Azoic on the west. These clays and sands also are very 
irregularly bedded. The sands especially, are much affected 
by cross bedding. From Alexandria northward the lower 
series is rarely seen, being too deeply buried. At Baltimore 
it appears in the lowest white clays and sands dug in the 
of the hills. Toward the close of the formation of these strata 
they were invaded by some agent which planed them off, or 
scored them more or less deeply into channels, and brought 
along with it quantities of sand, gravel, large rounded stones 
and slightly worn blocks, often of very large size. This mate- 
_ rial was deposited in a confused manner, and is usually very 
different from the beds on which it reposes. is agent seems 
_ to have acted from the northwest. From Fredericksburg to 
the Potomac, the gravel and rounded stones are composed of 
quartz, Potsdam quartzite, and sandstone. In the vicinity 
_ of Alexandria, Potsdam bowlders predominate over the quartz. 
_ They are commonly six or eight inches in diameter, and often 
_ attain the dimensions of one and two feet, showing frequently 
_ Scolithus markings. They are found over the surface of the 
_ Mesozoic here, five or six miles from the Potomac and up to 
_ the Azoic border, often forming belts of stones packed in com- 
- Minuted Potsdam matter. Throughout the entire belt, the 
large, slightly worn blocks, are composed of crystalline rocks, 
_ from varying distances to the west and northwest, all the way 
_ to the Blue Ridge. These are not rarely four or five feet in 
_ diameter, and sometimes six or seven feet. Near Fredericks- 
_ burg, we may see large stones formed of the characteristic 
epidotic and chloritie schists, composing the Blue Ridge on the 
west. Near Alexandria, large, slightly worn masses, having a 
diameter of four or five feet, are found of the peculiar siliceous 
oes not seem to have been confined, in all places, to the 
upper portion of the series. Near Neabsco Station, on the 
Fredericksburg and Alexandria Railroad, I found near the 
oic floor, and under a very considerable thickness of the 
upper sands and clays, a heterogeneous mass of angular Azoic 
matter in large blocks mixed with worn and rounded stones, of 
quartz and Potsdam sandstone, imbedded in blue clay. This 
