38 DEDUCTIONS. 



from the eastern side, except the talcose schist. 4. We get an approximate idea of the 

 amount of erosion from this part of the Green Mountains. We have flattened down the 

 curve described by the strata originally, more than perhaps we ought to do ; yet it seems 

 almost twice as high as Mansfield Mountain which is shown on the section at M, and is the 

 highest point in the chain. The erosion at Mt. Holly cannot have been less than 8000 

 feet, which is nearly six times as great as the present height of the mountain at the 

 summit level of the railroad. 5. We see here how the schists and gneiss may be formed 

 out of conglomerate. This is perhaps the most important inference, and therefore it will 

 be dwelt upon more fully in the sequel. 



We proceed now to draw some inferences from the facts detailed respecting the Ver- 

 mont conglomerates, additional to those already given. The Vermont localities teach the 

 same lessons as those in Rhode Island ; but we think they develop other conclusions. 



1. They show, we think, that the elongating and flattening force in Vermont must have 

 operated most energetically in the direction of the dip, whereas in Rhode Island it was 

 most powerful in the direction of the strike. In the latter case it was as if two men had 

 taken hold of the ends of a plastic mass and pulled it out horizontally : but in Vermont 

 it is as if one had stood at the top of a steep hill and the other at the bottom. This is 

 evident from the fact that when we look at the edges of the rock laid bare along the line of 

 dip, we see little more than the flattened edges of the pebbles in the form of folia ; but if 

 laid bare along the line of strike, we see the flattened and even lenticular ends of the 

 pebbles as shown on Fig. 17 already given. The fact, however, that the pebbles are 

 lenticular on the basset edges of the strata, show that the whole force was not exerted in 

 the direction of the dip. They were a good deal flattened horizontally, but more so 

 vertically. 



2. We think we get a glimpse in Vermont of the mode in which the force acted to 

 elongate and flatten the pebbles. We refer to the bowlder shown on Fig. 16, where it is 

 obvious that the bending of the rock, if it was plastic, would produce that effect, because 

 the outer portions must be extended over wider and wider spaces. Hence, as in the 

 figure, a pebble on the interior part might be only moderately extended, while the outer 

 ones were stretched almost into mere laminae. 



Apply now this principle to Fig. 18 which shows the manner in which, as we suppose, 

 the strata were folded over the top of the Green Mountains. The effect would be to 

 stretch them out more in the direction of the curve, or dip, than at right angles to it, 

 although the strain would spread them in that direction also, to some extent ; and it may 

 be that the irregularities that must have accompanied such great movements as the fold- 

 ing up of a mountain chain, would make the horizontal elongation in some places the 

 greatest. 



We do not assert that this explication of the phenomena is certainly the true one ; but 

 only that it shows one mode in which the process might have been performed. Whether 

 any horizontal flexure can be found in the Rhode Island rock, to explain the elongation 

 there, we are unable to say, because the theory was not in our minds when we examined 

 those rocks. 



3. The facts detailed disclose to us some of the modes in which the folia of the schists 

 and of gneiss may have been produced. The first mode is by chemical agencies. Out of 



