EROSIONS. 213 



found no pot-holes in the sides of this ravine, but every other mark of a former current of 

 water, which wore out the gorge, is seen on the surface. 



The highest point in the gulf, perhaps a mile south of Proctorsville, is 117 feet above 

 the old river bed at Duttonsville, or 792 feet above the top of Bellows Falls. At the 

 summit, the gorge shows a deposit of terrace materials how deep I cannot say. But the 

 fact is sufficient to show that no stream has passed through this gorge, since the last 

 emergence of the continent. But that Black River or rather the progenitor of that river 

 on a former continent once passed through that gorge, and was, in fact, a part of 

 Williams River, will be obvious by an inspection of the rough outline on Plate V. But 

 at what period of antediluvian history did this take place ? 



If the principle above alluded to be true, namely, that where more than one lateral 

 ravine, once the beds of rivers, open from a common valley that which is lowest was last 

 occupied by the stream then the Duttonsville gulf is more recent than the Proctorsville 

 gulf. I have inferred that the former was the bed of a stream on the continent which 

 immediately preceded the present. Was the latter worn out during the same period ; or 

 might it have been the work of a stream on a still earlier continent that is, the second 

 one anterior to the present? If we knew the depths of the detritus at the summit of the 

 Proctorsville gulf, it might aid in deciding this point. But I can hardly believe that its 

 depth equals the difference of level between the two gulfs. If not, then the Proctorsville 

 gulf must have been higher than the other during the period of emergence previous to the 

 present. The country below Proctorsville, also, must have been blocked up high enough 

 to throw the waters through the Proctorsville outlet. 



The amount of erosion since that time, on such a supposition, must have been enormous, 

 to bring the region below Duttonsville into its present state. And it would not be an 

 improbable supposition that the Proctorsville gulf, as well as the right hand branch of 

 the Duttonsville gulf, already described, may have been the bed of a stream on a conti- 

 nent earlier than the last. But I despair of being able to prove this decidedly by any 

 facts within the reach of present observation. And yet, those detailed above do appear 

 to me to prove at least a great difference in the ages of these two gulfs. But whether the 

 period between them embraced a submergence of the continent, is another question. To 

 be able to trace back with clearness erosions accomplished on even the last continent, is 

 more than I ever expected to be able to do. The above facts come nearer to extending our 

 vision across another mighty chasm, and witnessing events in surface geology upon a still 

 earlier continent, than any I have ever met with. But whether this be a problem resolv- 

 able by the geologist, I am in doubt. 



OTHER CASES OF OLD RIVER BEDS. 



These are quite numerous, so far as we have been able to trace them out, and we have 

 every reason to suppose that further research would bring to light many others. Those 

 which we shall mention, but in general not attempt to describe minutely, are of two kinds 

 as to the period in which they were formed, and the materials which have been cut 

 through. The first class have been formed in modified drift, usually in the gravel and 

 sand of terraces, or even in existing alluvial meadows. The second class have been 

 formed in the solid rocks, and of course are of far earlier date than the others. 



