126 J. ERNEST CARMAN Vol. XXII, No. 5 



small irregularities in the roofs of the former cavities. The 

 clay exists in masses two to three feet across and in such 

 quantity that in wet weather it causes considerable trouble 

 in the crushing plant, because it clogs in the crushing burrs 

 and prevents the rock from dropping into them. The larger 

 masses are dumped to one side by the steam shovel and not 

 loaded on the cars. 



At several places sand is associated with the clay and at a 

 few places there is gravel containing pebbles and cobbles, 

 some of the latter being four to six inches through. The most 

 common rock among the pebbles and cobbles is the Monroe 

 dolomite, but basalts, granitoids and foreign sedimentaries 

 exist. Some of the pebbles are well rounded and some are 

 subangular. All of this material is relatively fresh. Most 

 of the quarry face was a confused mass of blasted stone, but 

 where the form of the clay deposits could be determined it 

 was found that if gravel and sand exist they are at the bottom 

 and at most places are overlaid by the clay. A few cases of 

 very fine sand interbedded with clay exist. Surfaces of pro- 

 jecting dog-tooth calcite crystals are buried in the sand, which 

 can be cleaned away from around the crystals. 



One deposit in a tunnel in the rock gives such clear evidence 

 as to deserve special notice. The rock channel is three feet 

 six inches high and two feet wide at the widest part, and is 

 cut across at an angle by the quarry wall. In the bottom is 

 coarse gravel containing some cobbles up to six inches in 

 diameter. Above the gravel is about two feet of compact, 

 tough clay, blue in color, except for six inches at the top, 

 which is oxidized and yellow. Above the clay is an open 

 space about one foot high. The channel extends obliquely 

 into the quarry wall and at a distance of about five feet it 

 broadens out into a space four to five feet across, with about 

 two feet above the filling of clay. Farther in, the channel 

 narrows and the roof comes down until at a distance of about 

 20 feet from the quarry face there appears to be only four to 

 six inches of space above the filling. 



ORIGIN OF DEPOSITS. 



As to the origin of the clay deposits, it is evident that they 

 did not originate by weathering in place, but have been intro- 

 duced in some way. The characteristics of the clay suggest 



