GEOLOGICAL SOCIETY OP PENNSYLVANIA. 



253 



The section is divided into four principal spaces, distin- 

 guished by different colours, and by the numbers 1, 2, 

 3, 4. 



No. 1 commences farther eastward than our section 

 extends, and is composed of alternating strata of shale or 

 slaty clay and limestone, the former predominating. One 

 limestone bed marked b, is about 50 feet thick, and does 

 not show many traces of organic remains, except where 

 it has been weathered. Vide specimen 3, locality 6. 

 Some of the limestone strata are not more than 1 inch in 

 thickness, and are filled with shells of various kinds. 

 Vide specimens 1, 2, locality a. 



No. 2 has, I believe, no limestone. It consists almost 

 entirely of shale, but has towards the western extremity 

 occasional strata of argillaceous sandstone of small thick- 

 ness, alternating with and passing into the shale. Some- 

 times the sandstone contains many impressions of shells, 

 and other marine remains. Specimens 4, 5, 6, locality c. 

 Towards the western part of this division, the shale has 

 an uniform deep red colour. The thickness of the rocks 

 comprised in this division, measured perpendicularly to 

 the dip, is 5 feet and 1-lOth. 



No. 3 is composed of alternating strata of shale and 

 sandstone. Whole thickness 3370 feet. The sandstone 

 predominates greatly ; it is micaceous, and is readily 

 quarried in thin tabular plates of large dimensions. 

 Specimen 7, locality d. Towards the eastern part 

 of this division, the colour of the rocks is a deep red, 

 but it gradually changes to green, as we advance west- 

 ward. I could not discover any traces of organic re- 

 mains. 



No. 4. The coal measures. I have chosen to consi- 

 der them as commencing at the point e, because there is 

 at this place a decided change in the character of the 

 rocks, and we find, for the first time, sandstone contain- 

 ing vegetable remains of a kind which, I believe, is 



