JVotice of Hay den's Geological Essays. 55 



We think, that he has not conceded enough to the rava- 

 ges, comniitted by time, upon a part at least, of the stony 

 monuments of the globe, whether erected by the Creator or 

 by man. Stonehenge which he cites, (and which is not 

 granite, but sand stone,j is very deeply furrowed by time : 

 the angles are rounded, and the stones are evidently reduced 

 in size. The same thing is true of many of the ancient 

 cathedrals, castles, palaces, and other buildings in England 

 and Scotland. Where they have not been kept in repair by 

 assiduous attention, they are all in ridges, hollows, and prom- 

 inences, decisive marks of the tooth of time, and many 

 prominent parts of considerable size, are almost or quite de- 

 stroyed. 



Most of the public buildings in England, both ancient 

 and modern, are constructed of a calcareous sand stone, or 

 of lime stone of the secondary or transition class. 



In Cornwall, one of the granite regions of England, ex- 

 tensive ledges of granite, as we have seen, are crumbhng 

 down in a state of decomposition, and the granite of Limo- 

 ges, in France, from which their excellent porcelain clay is 

 derived, is decomposed in some instances almost to a clay. 



The degradation of hills and mountains is, we suspect, 

 much more considerable than he admits it to be. We could 

 take him to a place* where enormous broken columns of 

 greenstone trap, even twenty-five feet in diameter, are ly- 

 ing upon a declivity in just that confusion in which they 

 evidently fell, from some colonade of naked pillars, forming 

 a greenstone ridge, and yet the nearest ridge, which is ma- 

 terially higher, is a mile distant. The particular ridge from 

 which they originally fell, must have been, at hand,\ and al- 

 though its ruins are still there, the ridge itself has been de- 

 graded by time. 



Mr. Hayden has assembled a very instructive and enter- 

 taining collection of facts respecting the Deltas of rivers, 

 and generally concerning their alluvion, whether relating to 

 their banks or their embouchures. We conceive that he 

 has proved, that even these examples of alluvion are less 

 attributable to the agency of the rivers themselves, than is 



* The western declivity of Talcot mountain, ten miles from Hartford, ob 

 the Albany turnpike. 



\ Unless, indeed, Mr. Hayden would suppose, that eurrents had moved 

 tliese enormous masses from ssrae other place 



