210 I. C WHITE — THE MANNINGTON oil- FIELD* 



demonstrate the existence of one of those cross-cut waves, since their crests are 

 i like some of the main northeast and southwest anticlinals) often marked by a 

 simple flattening of the rate of dip along the latter. Professor < >rton would call 

 such a structure (where there is no reversal of dip, but only a change in rate) 

 a suppressed anticlinal, a very good name, for such it really is. 



"It follow-, of eourse, that as a synclinal structure may be converted into 

 an anticlinal one by the presence of the cross-cut wave, so the reverse may and 

 frequently does happen, of which we have a. notable instance in the region 

 immediately adjoining Pittsburg. Here the anticlinals all sink down toward the 

 southwest until we reach tin- bottom of a cross-cut trough, where they begin 

 to rise again toward Cannonsburg, the result of which is to flood all the porous 

 rocks under Pittsburg with salt water. The numerous wells drilled at Pittsburg 

 show a good reservoir (Mr. Ashburner's prime factor for gas wells) ; hut geological 

 structure dominates here as everywhere else, and Alls the reservoir with water, so 

 that the little uas obtainable is practically useless, though when structure has 

 elevated this reservoir out of the water at Tarentum on the north and Cannons- 

 burg on the south, gas is obtained in abundance. 



"Another cross-cut anticlinal passes along the Conemaugh rive)', intersecting 

 Leechburg and Butler, its path being marked by a line of gas wells across syn- 

 clinals as well as anticlinals. 



"Having now glanced at some of the general structural features under which 

 large gas wells are found, we shall consider a few of the individual arches and 

 troughs in order to illustrate some of the general principles to which reference has 

 been made. 



"Laurel Will "//</ Chestnut Ridgt Anticlinals. — The arches made by these great 

 axe- would, in my opinion, come under the ban of exception (c), and hence the 

 rocks would probably be fissured too much to retain large quantities of uas. This 

 i- only an inference from theory, however, since so far as I am aware only one or 

 two wells have been bored near the crown of either arch. One of these was 

 bored for oil in Monongalia county, West Virginia, when/ the Chestnut ridge axis 

 crosses Decker's creek, six miles southeast of Morgantown. This well began at the 

 base of the no. XI limestone and descended about 400 feet, and hence did not pene- 

 trate the great Murraysville gas horizon | first Venango oil sand). Whether or not 

 these large arches may furnish gas when they have flattened out to much lower 

 waves in northern Indiana and Cambria counties is a question that only the drill 

 can settle, though the fact that some gas was obtained at Cherry Tree, near the 

 Nolo anticlinal diet ween Laurel hill and Chestnut ridge), would seem to renderthe 

 hope not entirely groundless. In fact it is within the range of possibility (though 

 not probable) that if a hole were sunk to a great depth on these arches, where 

 they exhibit even a large development, uas might he found. The drill has this 

 question to settle yet, since the two deep wells drilled in the synclines at .Johnstown 

 and Wellersburg could not he expected to find uas. Those drilled in the Ligonier 

 valley were also in a syncline, and hence obtained only small quantities of gas. 



'' Coming still further westward we find that several wells have been bored along 

 the western slope of Chestnut Ridge, about half way down the dip from the crown 

 ofthearch. One of these on Deckers creek and two on ( 'heat river. We.-t Virginia, 

 found a considerable quantity of gas in no. XII (the first urea t gas horizon), but the 

 rock, as might have been expected, was filled also with water, which rendered the 

 uas useless. The wells bored under nearly the same conditions as to locations in 

 Westmoreland countv found very little gas. 



