INDUSTRIAL PROGRESS DURING THE YEAR 1875. cv 



of a few hundred feet, which there intervene between the 

 unconformable floor and the Pittsburgh seam. Beneath this 

 lower series in West Virginia is a still lower group measur- 

 ing 1200 feet in thickness with coal seams, and having at 

 the summit a heavy conglomerate sand-rock. These corre- 

 spond to the sub-conglomerate coals studied by Lesley in 

 Southwestern Virginia, and to the small coal-beds lately 

 found by the Second Geological Survey of Pennsylvania in 

 the division No. X., or so-called vespertine strata, which lie at 

 the top of the Catskill Mountain group of the New York 

 survey. This series has been studied anew by Professor 

 Hall and Mr. Sherwood, confirming the old view of its geo- 

 logical distinctness, which had been disputed. It has been 

 traced in New York as far north as Schoharie Countv, and 

 carefully mapped. Six distinct and nearly parallel ridges, 

 synclinal in form, with eroded anticlinals, have been observed, 

 some of them carrying in their shallow folds the vespertine 

 and umbral beds, which farther southward lie beneath the 

 anthracites of Pennsylvania. 



Andrews has inquired into the question of the supposed 

 equivalency of the coal seams of the anthracite region with 

 those of Ohio, Western Pennsylvania, and West Virginia, 

 which he regards as still undetermined. He concludes, more- 

 over, from the various conglomerates to be found at different 

 horizons in the coal-measures, that the so-called basal con- 

 glomerate in Pennsylvania can no longer be regarded as 

 marking a geological horizon, but has only a lithological sig- 

 nificance. 



The question whether the coal -formation of the Rocky 

 Mountains is to be classed with the cretaceous or the ter- 

 tiary has been much discussed during the past year, but ac- 

 cording to the late results of Major Powell the solution is very 

 simple. The workable coals, or lignites, as they are often 

 called, extend in this region throughout the whole of the cre- 

 taceous formation, which has a mean thickness of 6500 feet, 

 and through the inferior half of the tertiary, including the 

 Upper and Lower Green River beds (1500 feet), and the Bit- 

 ter Creek beds (3500 feet), making in all more than 10,000 

 feet of coal-bearing strata, which are overlaid unconformably 

 by newer tertiary rocks. There is, moreover, a want of con- 

 formity in this series between the Bitter Creek beds and the 



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