89 



reddened lump, ready to be reduced by the next winter's frost into 

 productive soil. By analysis recently made, 1 find that both the 

 greenish sandstone and the resulting soil, contain a sensible quan- 

 tity, sometimes two per cent, of lime. Should this be found by 

 further research to be an invariable ingredient of these valuable red 

 soils, we might, perhaps, be authorised in ascribing their productive 

 character, at least in part, to its presence ; and we would to a cer- 

 tain extent be enabled to compare these soils with one another in 

 agricultural value, by chemically examining them for lime. 



Portions of the red soil in Nelson and Amherst, arising from the 

 decomposition of a red sandstone and conglomerate before de- 

 scribed, contain lime in a still more considerable proportion. The 

 rocks from which they are procured, in some instances, present up- 

 wards of six per cent, of carbonate of lime. A specimen recently 

 examined, yielded me in one hundred grains, precisely G.75 grains of 

 this substance. 



OP THH VALLEY OF VIRGINIA. 



The sectional line crossing this region, to which the profile re- 

 fers, commences at a distance of two or three miles from the western 

 base of the Blue Ridge, this being the position at which the rocks 

 of the valley first become apparent. Of the character of the beds 

 comprised in this interval, we have no data enabling us to speak 

 with certainty, inasmuch as the fragments of sandstone derived 

 from the broken strata of that range, piled upon the subjacent beds 

 of the valley, entirely conceal them from observation. At other 

 points along the eastern edge of the valley, the interval thus hidden 

 from examination is not so wide, but in no place hitherto observed 

 have the rocks of the valley and those of the Blue Ridge been seen 

 in contact. This, as yet, undetermined ground, is therefore repre- 

 sented on the profile by a blank, at the western boundary of which 

 the valley rocks, w r here first observed, are represented as com- 

 mencing. Future observations throughout this curious district are 

 indispensable to an understanding of the true relation existing be- 

 tween the formations bounding it on either side, and will accord- 

 ingly present subjects of geological, and even of practical interest 

 in the prosecution of more detailed research. 



As the profile indicates, beds of slate and limestone, in alternate 



12 



