Geological Papers. 119 



sand, cemented by oxid of iron, both of which are insoluble, there- 

 fore the water is practically as soft and pure as cistern water. 



The soil formed from the decomposition of the sandstone forma- 

 tions gives a poor soil on the ridges for agricultural purposes, but is 

 adapted to fruit-growing and some vegetables. 



Both the sandy formations, but especially the upper one, are 

 covered with a shrubby oak called "Black Jack." This often af- 

 fords a means of seeing for miles the trend of the formation. 



Many mounds are found, especially east of the upper sandstone 

 escarpment. In these mounds, especially around Elk City and 

 Niotaze, the sandstone which caps them is often found dipping 

 and fractured in one direction for a few rods, and then in another — 

 for example, the Oliver mound, two miles west of Elk City. In 

 going from the valley to the top of this mound we pass first'over 

 shale, then over the blue limestone about fifty feet above^the river 

 bottom, then again shale, then the massive sandstone, which is found 

 to be broken and dipping towards the hill. Here are found three 

 benches, the sandstone capping each. Considerable quarrying has 

 been done in each bench, and thus an opportunity is afPorded for 

 accurately observing the lay of the sandstone. In the highest part 

 of the mound, that is, the highest bench, the sandstone was found 

 to be horizontal, but in the others to be greatly disturbed. How- 

 ever, an examination showed that the blue limestone was undisturbed 

 and on the same level in this mound as in the others in this vicin- 

 ity, showing that the disturbed sandstone was local and caused by 

 the soft, clayey shale underlying the sandstone pushingl^out and 

 being eroded away, thus causing the massive slides in the hard 

 sandstone above the shale. 



Another example is the mound one mile north and west of Elk 

 City. This mound has the appearance of a "hogback" from the 

 river bottom. When going onto this mound at the lowest point we 

 find a heavy layer of sandstone horizontal, capping a narrow^ridge, 

 say thirty feet wide. Going southeast for 300 yards to a point 

 some twenty feet higher, we find the characteristic blue limestone 

 on the same level as in the Oliver mound. The layer of sandstone 

 five to ten feet thick is the sandstone found always under the blue 

 lime. Going northeast, to the highest part of the mound, we find 

 the sandstone dipping sometimes in one direction and then in the 

 opposite. However, the blue lime was traced all around the mound 

 and found to be undisturbed, save in a few places, where it was 

 evidently covered by sandstone from above; or in some instances 

 landslides have pushed the lime down the hill; but in all cases this 



