334 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.] 
The producing formation was penetrated to a depth of only 30 feet. 
The oil is described as a high-grade 42 per cent lubricating oil. Very 
little gas was encountered, and no determinations of pressure or vol- 
ume were made. 
NATURAL GAS. 
Some years ago a considerable pool of natural gas was struck in the 
"Jumbo" gas well, near the Woolley coal mine, at Petersburg, but 
although considerable deep drilling was done at various times about 
Petersburg, Oakland City, Princeton, and other points in the region, 
no commercial pools were developed. The "Jumbo " well, after flow- 
ing for a time, ceased to produce, but has since been cleaned out and 
now supplies the illumination for the town and furnishes the fuel for 
several hundred gas stoves. It is said to show a rock pressure of 585 
pounds. A new well was being drilled at Petersburg during the sum- 
mer of 1002. 
CONDITIONS FAVORABLE TO SUCCESS IN DRILLING FOR OIL OR 
GAS. 
While it is probable that similar if not greater pools may occur at 
other points in this region, their position can not be predicted in 
advance of drilling. The positions which are geologically the most 
favorable for drilling are the low anticlinal swells and the areas along 
the strike lines of the rocks just east of the points where their west- 
ward dip changes from flat to steep. Maps showing, by means of 
underground contours drawn on the Petersburg coal, the structure of 
the rocks in Pike, Warrick, and parts of Vanderburg, Spencer, and 
Dubois counties have been recently published by the United States 
Geological Survey." 
STRUCTURE. 
The general strike of the beds in southwestern Indiana is nearly 
north and south. Although there are many irregularities and even 
reversals of the dip, the general inclination of the rocks is commonly 
not far from due west. The amount of dip varies from 10 to 40 feet, 
with perhaps an average of about 20 feet to the mile. 
Among the more noticeable of the irregularities shown by the 
structural contours of the published maps of the Ditney folio are the 
shallow synclinal troughs near Littles, Ayrshire, Winslow, and near 
the county line north of Scalesville, and the low anticlinal swells 
northwest of Glezen, between Oakland City and the Patoka River, 
south of Winslow, near Arcadia, and southwest of Boonville. The 
crests of the swells afford, from a geologic standpoint, the most favor- 
able locations for gas wells, while their flanks afford the most promis- 
ing points for oil wells. 
P 
a Geologic Atlas U. S., folio 84, Ditney. Descriptions by M. L. Fuller and G. H. Ashley. 
