A GEOLOGICAL HISTORY. 45 



glomerate of Limestone, quartz and argillitic peb- 

 bles ; then again the conglomerate of the Potomac 

 is of different kinds of coloured Limestone with 

 few quartz ; one of the colums in " the House of 

 Representatives" at Washington City has a quartz 

 pebble in it, which may be seen by its projection 

 above the other parts of the surface of the column. 

 As this faint and interrupted, thin streak of " the 

 Coal Measures," is lying superincumbent to this 

 Sandstone, it cannot belong to it, but to the Coal 

 Measures the same as those of Virginia. The 

 " rain marks" of this formation, so often spoken of, 

 appear to be formed thus — at Belleville, Newark, 

 and Patterson, where the Sandstone is quarried in 

 a large way, the stratum lies nearly horizontal, or 

 with but little dip ; the thickness of each layer is 

 from one inch to four feet and sometimes as thick 

 as six feet ; between each layer is a ferruginous 

 chocolate brown or red clay, this clay lies between 

 most of the layers, (I have seen it where it is 

 quarried to 25 feet depth, passing through eight 

 or ten, or more of those layers,) and if any person 

 will take the trouble to examine the under surface 

 of each layer, as well as the upper, they will find, 

 that on both surfaces of these layers, the marks 

 exist. At every certain deposit of the sand of 

 more or less thickness, there was a deposit of 



