1876.] 281 [Niles. 



and horizontal strata, the border and the interior of the continent, 

 hill, valley and plain, furnish alike examples of its activity. 



The uninterrupted existence of this force under such varying and 

 diverse conditions shows that its cause is neither a fluctuating nor a 

 narrowly limited one, and we therefore seek an explanation in some 

 of the grander changes in the earth's progress. 



The modern view of mountain-making by lateral movements is 

 based upon facts which are regarded as evidences that just such 

 events as these have occurred in the past. It will be observed that 

 the dislocations shown in the broken, faulted, inclined and folded 

 strata, and which enter into the fundamental features of the earth, 

 are reproduced in miniature by this geological force of the present 

 time, and thus it may be regarded as an exhibition of what is con- 

 ceded to have been the agent of like events in the past. 1 am there- 

 fore convinced that the lateral compression exhibited at Monson, 

 Berea, and other localities, is the continued action of the same geo- 

 logical power which has been the chief agency in the elevation of 

 continents and mountain systems. If this conclusion is correct, and 

 if we accept the common belief that the contraction of the globe has 

 been the cause of the ancient movements, we may regard the present 

 energies of the force as proceeding from the same general cause. 



It does not follow, however, that the contraction of the earth must 

 be simultaneous with the latest manifestations of the force, for the 

 observed facts demonstrate the compressibility and elasticity of the 

 rock, hence the compression may considerably precede the expansive 

 movements. 



But it will be observed that, at this time, the force is not exerted 

 perpendicularly to the great mountain axes of the continent, hence 

 the direction has been changed. But if we recall the physical his- 

 tory of the North American Continent we shall remember that just 

 this change in the direction of the force was established at the 

 close of the Tertiary, and it has determined the character and posi- 

 tion of the subsequent elevations and subsidences. To have caused 

 the changes of level in the northern part of the continent during the 

 Quarternary Age, the power must have been exercised in nearly or 

 precisely the same direction as at present, that is, parallel with the 

 meridian. It is reasonable to expect the present operations of geo- 

 logical power to correspond in direction with those of the later, 

 rather than those of the earlier periods. We may therefore reason- 

 able claim the direction of the present actions as one of the evidences 

 of the identity of the power. 



