Claypole.l 5d-J [Oct. 20, 



greatest breadth, and is apparently intended to represent a cap of that 

 formation overlying the Chemung of the same township. 



The existence of this cap of Catskill, or at least of a great part of it, is 

 beset with numerous difficulties to one who is familiar with the ground, 

 and during my recent visit in Bradford county I became strongly sus- 

 picious of the accuracy of the map. The following consideration was 

 very weighty in this direction. 



The Chemung rocks all along the north bank ot Towanda creek dip to 

 the south at angles varying from 90° to 15^. At Leroy, the former oc- 

 curs, and east and west of Leroy the dip flattens down, but not regularly 

 to the latter figure. The dip also flattens down as one recedes from the 

 road and goes northward, but very gradually, so that at Leroy it does not 

 disappear, and render the strata horizontal in less than a mile. 



With this inclination of the beds and with the highest beds of the Che- 

 mung far out in the valley, probably in the west end of it on the south side 

 of the Towanda creek, it seemed quite impossible that any such mass of 

 the Catskill could occur capping them so near the road upon the north 

 bank. The generalized section along the valley is given in Fig. 2, 

 page 535. 



When it is recollected that the total thickness of Chemung rocks between 

 the top of the group at a, and the horizontal exposure at b, must be at least 

 1500 leet, and is probably more, the difficulty of realizing a cap of Catskill 

 on the top of a hill only 200 or 300 feet high becomes obvious. 



Aside, however, from all antecedent and theoretical considerations, it 

 was desirable to obtain the evidence of actual observation, in order to as- 

 certain the truth, and also, if possible, to detect the cause of the mistake, 

 if mistake had been made. On the morning, therefore, of leaving Leroy, 

 I obtained the assistance of Mr. A. T. Lilley, a gentleman Avell acquainted 

 with the district and with its geology, and set out to investigate the 

 ground. 



Leaving Leroy by the Towanda road we first established the fact that 

 lower and lower beds of the Chemung come continually out of the hill- 

 side and point out into the vallej^ for several miles, throwing the Catskill 

 farther and flirther to the southward, and giving a constantly thickening 

 mass of Chemung to be placed on the hill -top, before the summit of that 

 group could be reached. Turning to the northward up a road about one 

 mile east of West Franklin, we followed it for nearly half a mile, until we 

 attained an altitude of about 150 feet or more above the valley. The 

 whole country on both sides of the road was deeply covered with drift, 

 and no bed-rock whatever was visible anywhere. Nor was a scrap of the 

 red Catskill sandstone to be found lying loose on the ground. Xot only 

 is it perfectly certain that no Catskill exists in place along this road (which 

 follows a small run), but it is equally certain that many hundred feet of 

 Chemung rocks are missing, and must be added to the top of the hill before 

 the base of the Catskill can be reached. Yet this road on the map is drawn 



