10 ECONOMIC GEOLOGY OF AMITY QUADRANGLE, PA. 
and deepest valleys in this quadrangle is moderate, being about 700 
feet. A great many creeks and their tributaries dissect the region 
into hundreds of sharp ridges or knob-like hilltops, with steep slopes 
extending to the bottoms of ravines which cut up the territory in 
every direction and make it very rough. 
The features of greatest importance in the development of the 
region are the main valleys. Along them the principal settlements 
are situated, and they are also generally utilized for through lines of 
travel, both wagon roads and railroads. For instance, the valley of 
Chartiers Creek furnishes sites for the towns of Washington and 
Houston and a direct route for the branch of the Pittsburg, Cincin- 
nati, Chicago and St. Louis Railroad connecting with the city of 
Pittsburg. The valley of Peters Creek and part of that of Little 
Chartiers Creek are occupied by the Baltimore and Ohio Railroad 
for its route between Pittsburg and Wheeling by way of Washington. 
Tenmile and Little Chartiers creeks and all their larger branches are 
followed by main wagon roads, and in time they will doubtless be par- 
alleled by railroads. Tenmile Creek affords a specially favorable 
route for entering the southern part of Washington County by way 
of Monongahela River. 
Of greatest importance are the relations of the topography to the 
coal industry. The Pittsburg coal bed, which is the most valuable 
seam in southwestern Pennsylvania, outcrops for several miles along 
Chartiers and Peters creeks, and here it is possible to mine it by drift 
and slope with little difficulty, and the small mining settlements of 
Meadowlands, Anderson, Venetia, and Hackett have sprung up. In 
portions of the quadrangle where this seam does not outcrop the 
valleys naturally form the most favorable locations in which to reach 
it by shafts, and hence operations have been conducted on Pigeon 
Creek for several years. This creek flows eastward into Mononga- 
hela River and forms a convenient route by which a branch of the 
Pennsylvania Railroad reaches the mines. The valleys of Little 
Chartiers and Tenmile creeks are suitable for this same purpose. 
Within the last twenty years oil and gas have been discovered in 
paying quantities beneath the Amity quadrangle, and drilling has 
been conducted on a large scale. In prospecting for oil and gas the 
valley bottoms are naturally chosen as the first sites for wells, because 
the expense and time required to drill through several hundred feet 
of rock in the hills are thereby saved. As development of the field 
progresses, the position of the oil or gas belt becomes better known, 
and later wells, being drilled in the most favorable positions for find- 
ing the oil without regard to topography, are widely scattered over 
the hills. Hence, it is apparent that the topography has very little 
practical effect on the oil and gas industry. The valley of Chartiers 
Creek, between Meadowlands and Houston, is the site of many large 
