Lyuian.] J-*^^ [May 18, 



by other conjectures, there may yet be fouud some convenience in the 

 present collation of facts. 



New conjectures are still necessary owing to the imperfection of the 

 record of facts outside of Pennsylvania. Although the New Red stretches 

 for hundreds of miles close past some of the most populous parts of Amer- 

 ica, the probable economic resources never seemed enough to secure its 

 thorough examination and a publication of the results. Even as regards 

 field work it has been a sort of play-ground for geologists rather than a 

 place for thoroughgoing investigation. The Slate governments to this 

 day, with all their surveys, have never fully provided the means for such 

 work. What little field work has been done, outside of Pennsylvania, 

 has been, in"''great part, carried out with the exaggerated idea that the 

 geology of a region can be studied out merely by a comparison of the fos- 

 sils, a far shorter and easier way than the laborious methods of properly 

 geological observation and collation. Such purely paleontological geolo- 

 gizing may be likened at its very best to the rapid hypsometrical work of 

 the aneroid instead of the spirit level ; and exclusive dependence on the 

 fossils for geological indications may be compared with confiding in 

 pocket-aneroid work more than in railroad leveling. Furthermore, the 

 paleontologists have not merely altogether neglected to plot numerous 

 dips as an indication of geological structure, but they have not generally 

 thought it worth while to indicate with any sort of precision the beds that 

 have yielded their fossils ; though Fontaine has done something of that 

 kind. Wheatley, alone, gave a measured columnar section of about 180 

 feet, showing clearly the position of his fossils ; but he miist have been 

 more a geologist than a paleontologist. 



The Pennsylvania foundation of the present conjectures is, however, 

 far from conjectural. We are not here entering upon another system of con- 

 jectures based on conjectures, but conjectures based at least on facts ; and it 

 is to be hoped that the conjectures themselves may prove to have nothing 

 improbable, violent, unnatural or supernatural in them. The unexpect- 

 edly great thickness of the New Red in Montgomery and Bucks counties 

 is not conjectural, but has been ascertained by means of much careful, 

 laborious, time-taking work in the field and in the oflice. Something like 

 one-half of the field was excellently mapped with ten-foot contour lines by 

 the Philadelphia Water Department several years ago, and the rest was 

 roughly contoured expressly for the New Red investigation, and the com- 

 pleted map of it was in part replaced by some United States geological 

 work just then published. Some two thousand dips were plotted on the 

 map. Some two thousand rock exposures, including all the railroad cuts 

 and many long river-side cliffs, were observed, measured roughly and 

 drawn in columnar section to scale. Besides the written description of 

 each rock-laj^er, some four thousand rock specimens wei'e taken for a 

 more complete understanding and for comparison one with another. A 

 general columnar section was formed by combining the separate ones, 

 computing the intervals between them, having due regard to the dip, 



