350 EXPEDITION TO THE 



connected with the view of a primitive formation which 

 we had not seen since the first five days of our journey j 

 but it resulted also in a great measure from the certainty 

 that we had at last arrived at what we had long been look- 

 ing for in vain. We had traced those scattering boulders, 

 which lay insulated in the prairies, from the banks of the 

 Muskingum to this place. We had seen them gradually 

 increasing in size and number, and presenting fewer signs 

 of attrition, as we advanced further on our journey. Two 

 days before, their number, size, and features, had induced 

 the geologist of the party to predict our speedy approach 

 to the primitive formations, and it was a pleasing confir- 

 mation of his opinions to find that these rocks had really 

 been seen in situ, within thirty miles, in a straight line, of 

 the place where he had made this assertion. The charac- 

 ter of these rocks was examined with care, and found very 

 curious. It seemed as if four simple minerals, quartz, feld- 

 spar, mica, and amphibole, had united here to produce al- 

 most all the varieties of combination which can arise from 

 the association of two or more of these minerals ; and these 

 combinations were in such immediate contact, that the 

 same fragment might, as we viewed one or the other 

 end of it, be referred to different rocks ; while in some 

 places granite was seen perfectly well characterized, va- 

 rying from the fine to the coarse-grained ; in others, a 

 gneiss, mica slate, greisen, (quartz and mica,) compact 

 feldspar, (Weisstein of Werner,) sienite, greenstone, and 

 the sienite with addition of quartz, forming the amphibolic 

 granite of D'Aubuisson, were equally well characterized. 

 The only rock composed by the union of two of these 

 principles which we did not observe, but which may per- 

 haps exist there, is the graphic granite, (Pegmatite, Haiiy.) 

 These rocks are not very extensive ; the circumference 



