KIchards.] 200 [November 18, 



disappeared, or so nearly disappeared that it does not exceed in 

 thickness many of the lesser beds. In a region subject to such nu- 

 merous and rapid changes, questions of structure cannot be settled by 

 superficial examination. In the southeastern district, where the ex- 

 plorations have been made with a patient attention to details, and 

 where the profiles are very numerous, this diversity of structure is 

 made perfectly manifest. 



The profiles on page 242 show from seven to eleven seams of coal 

 between the Putnam Hill limestone and the Pomeroy coal, which is 

 regarded as the equivalent of the Pittsburg.. Adding three for lower 

 beds, there are ten to fourteen in all. Of the many sections made in 

 all parts of the Ohio coal field, it is doubtful if two can be found 

 which are more than five miles apart, that will match each other in 

 all respects. If there is any rule of structure in the Ohio series, it 

 is a rule of want of persistence, such as Prof. H. D. Rogers recog- 

 nized in western Pennsylvania. Can these results be accounted for 

 by assuming the existence of regular waves, folds and undulations, 

 due to mechanical disturbances after the deposition of the coal? 



On a Newly-discovered Lead Vein in Newburyport, Mass. 

 By Prof. Eobert H. Richards. 



In the early part of the month of August, 1874, I was shown a 

 specimen of galena, which purported to come from near Newbury- 

 port. The specimen was much weathered on its surface, but never- 

 theless I was able to recognize galena, gray copper (tetrahedrite), 

 and pyrite. The galena was rather fine in texture and columnar in 

 structure; altogether the ore reminded me very much of the rich 

 silver ores of Georgetown, Colorado, which are often composed of 

 identically the same minerals. 



A day or two after, (August 8,) I accompanied Dr. E. J. Kelly to 

 the locality whence the specimen was taken, which is about two 

 miles southwest of Newburyport, in the town of Newbury. In a barn 

 near by there was a pile of the ore containing about four tons. This 

 ore was composed of the same minerals as the previously mentioned 

 specimen. The rich piece of tetrahedrite, whose analysis is given 

 further on, was selected from this pile. The owner of the land in- 

 formed us that the pit had been dug during the spring to the depth 

 of six feet, and that further sinking was rendered impossible by 

 water. 



