44 GEOLOGY OF THE SECOND DISTRICT. 



the fluid mass exerts comparatively but little influence on the adjacent rock. That a narrow 

 dyke of granite, even thougli fused and perfectly liquid, should melt an adjacent mass of lime- 

 stone far more extensive than itseif, is a view which is contrary to analogous facts ; and that 

 wide belts of transition or of blue limestone should have been so perfectly melted as to flow, 

 and incorporate itself with other rocks, by a few dykes of granite, seem to be effects too great 

 for the cause assigned. Melted lava is an instance of this kind : the surface cools, and be- 

 comes sufficiently firm to support the weight of a man, while the interior is in a melted state. 

 In some instances, so feeble is the effect of injected masses on the adjacent rock, that it is 

 difficult to satisfy ourself that it has been acted upon at all. Remarkable examples of this 

 character are abundant in the vicinity of Montreal, where the Trenton limestone is traversed 

 in all directions by dykes, which must have been melted when injected, as they contain crys- 

 tals of pyroxene, feldspar and tremolite ; yet the effects on the limestone are scarcely per- 

 ceptible, and not a solitary crystal is produced in the limestone near the line of contact, nor 

 is the limestone in crystalline particles itself. 



To account, then, for all the facts and phenomena which primitive limestone exhibits, I find 

 it necessary to adopt other views than those which are contained in the preceding extracts 

 from the published opinion of those eminent geologists whose names appear on these pages, 

 and with whom it is always pleasant to agree ; and here I may be permitted to say, that the 

 only theory which meets all the difficulties of the case, is the one I have proposed. Not that 

 limestone never ajjpears as an altered rock ; for being a sedimentary rock also, it must be 

 liable to all those agencies to which other sedimentary rocks are exposed. But this by no 

 means alters the question of its original state and condition, any more than it docs that of 

 granite, when the sandstones which are derived from it are melted and fused, so as to re-form 

 the rounded pebbles again into a perfect mass of gi-anite. To one who is disposed to doubt 

 in this matter, let him ask himself where all the limestone came from which constitutes so 

 large a proportion of all the rocks of the globe : it is diffused universally. In the primary, 

 transition, secondary and tertiary, it enters largely ; there is even an enormous quantity of 

 calcareous matter in the chalk, lias and oolites of the secondary. 



There is one point in the Report of Prof. Rodgers, to which I may call the attention of 

 geologists, which bears upon the questions at issue : It is the diversity of dip between what is 

 called, in the Report, the hLuc limestone, and the altered or crystalline mass ; with which, in 

 case the latter was a continuous portion of the former, we should expect it would coincide. I 

 will extract tlie two passages in the report, which contain the statements to which I refer : 



" • The narrow valley embraced between those hills and the Wallkill mountain on the 

 " southeast, is in the immediate neighborhood of Sparta, and for some distance southwest, 

 " occupied by the unaltered blue limestone dipping usualhj towards the northivest. Again, 

 " notwithstanding the prodigious extent of igneous action to which the limestone has been 

 " evidently exposed in these belts, manifested by the width of the space over which a total 



♦ Prof. RoDGKKs's J'mai Repojl, N. J. p. 72 and '6. 



