150 Prof. Rogers's Address before the 



structures we first meet with have too much the features of the present 

 day deeply to move our minds ; but far towards its sources, on the very 

 confines of the great desert of the forgotten past, monuments are found, 

 that", by their strange outlines and dim inscriptions, calling conjecture 

 to the aid of thought, stir in us a curiosity which belongs to the pro- 

 foundest part of our intellectual and moral nature. The whole history 

 of geology is the record of a series of successive incursions into re- 

 moter and remoter provinces of time. Pushing research to its limits, 

 we seem nearly to have reached the bounds of the accessible past, in 

 the diminution, and at last the total disappearance of fossils in the earlier 

 strata. Our science has reached the point just attained by geography. 

 No conjectural continent is left for a geological Columbus to discover 

 — no great region remains unvisited, and no principal boundary un- 

 drawn. The business of the present and future generations of geolo- 

 gists, is to establish with all the precision admissible, by science, the 

 exact limits which divide the many districts of ancient time into which 

 they have penetrated ; to define the position, so to speak, of each 

 known coast, and to bring to light such lesser districts as may yet lie 

 undiscovered within their more conspicuous borders. This work, more 

 difficult by far than that of mere first discovery, since it demands a very 

 thorough knowledge both of palaeontology and of structural geology, 

 is advancing at this time with extraordinary speed in Europe, in the 

 hands especially of Phillips and De la Beche, Murchison and Sedg- 

 wick, De Beaumont and D'Orbigny. 



Let us inquire how far we in the United States have proceeded in 

 the same labor, of firmly establishing some of the more important lim- 

 its betweea the several portions of geological time, as recorded by our 

 sti-ata and their organic remains. And first, let us examine the con- 

 clusions reached regarding the commencement or dawn of the whole 

 fossiliferous period. The fixing of a base for the palaeozoic rocks of the 

 United States, is a problem scarcely less difficult than that of determin- 

 ing the lower limit of the corresponding system in England, to which 

 the admirable sagacity of Sedgwick has been so usefully directed. 

 Do we possess in the so called Taconic system of rocks lying to the south- 

 east of the unequivocally fossiliferous strata at the base of the New York 

 or Appalachian system, an independent mass of formations, of an un- 

 questionably earlier date, or are these on the other hand, but well known 

 lower Appalachian strata, disguised by some change of mineral type, 

 and by igneous metamorphosis. These Taconic rocks under the form 

 they assume along the eastern boundary of New York, and the western 



