1892] MARYLAND ACADEMY OF SCIENCES. 191 



ten to twenty feet thick, and this last is overlaid near or 

 at the surface by fonr to six feet of the small quartz gravel, 

 which is generally spread on the hills of this region. 



The entire series in this region is thus seen to be Albi- 

 rupean. No sign of the " Variegated Clays " appears in 

 any group of these deposits, and they can all be matched 

 in the Kound Bay part of Maryland, which overlies the 

 genuine Potomac formation. The Woodbridge Clays like- 

 wise belong to the Albirupean formation, and most of them 

 are included in the section reported above. Texture and 

 composition go far in identifying the clays and clay-sands 

 of all the above regions of New Jersey, and color and its 

 distribution are not of much value in discriminating the 

 different types of these materials. 



As examples may be cited the basal white clays of the 

 Sayresville district. There, in several exposures, portions 

 of the beds are stained red throughout a stretch of many 

 feet, and in parts of the very same strata a sort of red or 

 yellow marbling appears, which gives much the same effect 

 as does the true Variegated Clay. 



The marshes of the Delaware river between Chester 

 and Wilmington have evidently been cut through the 

 Alternate Clay Sands, since some of the clays and sands 

 on which they rest are exposed in excavations of the 

 surface. They occur in the same order of superposition 

 in both Maryland and New Jersey, so that a section 

 taken at the head of Kound Bay, on the Severn river, 

 Maryland, will serve as a type of the formation wherever 

 it occurs. Thus, at the last named locality, we observe a 

 stratum of clean white sand extending below tide level, 

 which rests upon plastic Variegated Clays that rise into 

 hills when the Severn river is ascended a short distance. 

 These " Variegated Clays " become dark lead-colored in 

 some localities, as above the "Iron Ore Clays" in the 

 region between Baltimore and Washington. Their equiva- 



