OliSEKVATIuNS 

 On the geological features of the post- i 

 of the city of Albany, and its li. ; 



The Helderberg mountains occupy a position compri- 

 sing about one-third part of the entire county of Albany. 

 They lie in a southwesterly direction from the city, twelve 

 miles distant ; and may be seen, on a clear day, to form a 

 beautiful feature in the landscape scenery from any of the 

 public highways. Tlie otlier [tortions of the C(iunty j. re- 

 sent the appearance of a uiiilnrm U-ve] plain nf ^.-nd. aliiu^t 

 completely covered over by a (iniM- -i-wtM ><\' ; in.-. wi'Ai 

 oak,and other deciduous li. ; • >;.(t:-n, 

 particularly along the coin M \i -liawk 

 rivers, and most of tlie niin.^i ^ :uctlieir 

 waters into these <•]; -•:' , .-jn-c 



base of the couiiti \ 

 stones and shales. 



system sometimes j i r 

 of blue and drab-colored clay > ; the latter emhrarin- all 

 over among its different strata, innumerable beds of sand 

 and gravel, the whole mass belonging evidently to a more 

 recent, or post-tertiary period. Above this is spread out 

 a continuous stratum of yellow ferruginous sand, which 

 forms the surface of the plain ; and however level may 

 appear to be the surface of this plain from a distant point 

 of view, a nearer examination will disclose frequent hills 

 of sand and depressions of morass, the former drifted up 

 by the winds at a period of time long before vegetation 

 had scattered a single seed upon the soil. 



The general elevation of the surface of this ]»Iain has 

 been ascertained, by actual measurement, to be about two 

 hundred and sixty feet above the tidal wave. 



The clays which constitute this formation are about one 



