1899] Geological Society of America. 197 



out the length of the valley. A complete section is afforded from the base 

 of the Black River formation through the Trenton and terminating in the 

 Utica. Species hitherto reported only from Canadian localities are 

 found associated witii those characteristic of the Trenton Falls type- 

 province, showing the Champlain connection of Ordovician seas. 

 Several zones characterized by restricted species are located, and also 

 "conglomeratic zones." The fauna is very abundant and supplies a 

 basis of comparison for similar detail study from other provinces. The 

 occurrence of the Hudson River and Oneida groups in the region is 

 questioned. 



The repeated statement of many geologists that the Utica of the 

 Lake Champlain Valley is everywhere found lying uncomformably over 

 the Trenton is no doubt based on accurate local observation. It must not 

 be argued however that the Utica is thus related to the Trenton. 

 Dr. T. Sterry Hunt us^d to insist that the Utica and Trenton were not 

 conformable to each other and connected by passage beds. If such 

 be the case in the Lake Champlain region, such a view cannot for a 

 be held in a basia like the Ottawa Palaeozoic Basin. The occurrence, 

 relative abundance or paucity of certain forms at different horizons 

 in the Trenton of the Lake Champlain Valley showed considerable 

 variation as compared with forms found by us in the Ottawa and 

 St. Lawrence Valleys. 



"Structure of the lola Gas Field, Allen Co., Kansas." 



By Prof. EDWARD ORTON, Columbus, Ohio. 



The followmg is the abstract submitted by Prof. Orton, the most 

 eminent authority on " Natural Gas." — Natural Gas is more widely 

 distributed, geologically and geographically, and exists in larger 

 quantity than any one would have claimed twenty or even ten 

 years ago. Its productive horizons cover the entire palaeozoic 

 column of the country. Cities supplied, at least partially, with natural 

 gas for fuel and light are no longer uncommon. Two distinct divisions 

 can be made of gas accumulations, viz. : That which is stored in im- 

 pervious rocks as shales, most limestones, etc , and that which is found 

 xn porous rocks. These divisions maybe provisionally styled Shale 

 gas and Reservoir gas : each having characteristics of its own. Shale 

 gas occurs in comparatively small wells. Its wells lack uniformity of 

 rock pressure. It does not occupy definite horizons; it exists mde- 

 pendently of petroleum in many cases, has staying properties — does not 

 depend on the structural arrangement of the strata that contain it. 

 Reservoir gas is found in great wells ; approaches uniformfty of rock 

 pressure in each subdivision of territory, occupies definite horizons, is 

 accompanied by oil, its wells generally come to a sudden end — is 

 entirely controlled by the structure of the rocks in which it is accumu^ 



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