"SLIDES" IN THE CONEMAUGH FORMATION 355 



likewise the obstruction or falling in of roads. The frequency, 

 however, is itself the safeguard, the population having become edu- 

 cated to the danger, and consequently taking proper caution. 

 The injuries from such causes have been few. 



It may be noted that slides have never been of sufficient extent 

 to interfere with the use of the Monongahela River since rendered 

 navigable. 



The only direct economic benefit from the slides Hes in the fact 

 that brick, ordinarily made by grinding the shale, can be made of 

 almost equally good quality and less expense for handUng from the 

 sHde material. When work in the shale is interfered with by sUdes, 

 the material in these is used. 



The shales worked at present near Morgantown are near the base 

 of the Conemaugh, though shales higher in the formation are fre- 

 quently used elsewhere. Formerly brick was made from river- 

 terrace clays, these clays resulting doubtless from the assortment 

 of shale muds reaching the rivers as sHdes and from direct stream 

 action. 



