20 UNIVERSITY OF MISSOURI STUDIES 



grains are about .3 to A mm. in diameter. On weathering the 

 glauconite is partially replaced by limonite. 



These sandy beds are very thin, but each layer shows still 

 finer laminations which are caused by variations in the amount 

 of glauconite present, and by the crystallinity of the dolomite, 

 some layers having a medium granular texture, while others are 

 fine-grained. Ripple marks are abundant in these beds. The 

 sandy beds are usually not more than a few inches thick. 



The "edgewise" conglomerates are interesting since they in- 

 dicate shallow water. The conglomerates are rarely more than a 

 foot in thickness and most of them are only four to six inches. 

 As noted above, most of them are lenticular, and are found espe- 

 cially in the lower part of the formation. The conglomerates 

 are greenish-red to greenish-gray in color. Some are fairly dark, 

 but the majority are of the lighter shades. The rock consists of 

 pebbles of the underlying, thin-bedded glauconitic, sandy dolo- 

 mites, the pebbles ranging from one inch to four or five inches 

 in length and from a quarter to a half inch in thickness. They 

 are rudely oval in outline. The comers are rounded off, but not 

 very perfectly (PI. Ill, A). 



Most of the pebbles are rudely parallel to each other and to 

 the bedding planes ; but in some of the beds, especially in those 

 higher up in the formation, they lie in all possible positions. 



There does not appear to be any difference in the crystalUn- 

 ity between the pebbles and the matrix. The pebbles are dis- 

 tinguished in the unweathered conglomerate by being darker in 

 color than the matrix. Under the microscope the pebbles are not 

 only darker, which is due to their containing more kaolin, but 

 the grains are also smaller than those in the matrix. One of the 

 pebbles contains distinct evidence of organic remains which are 

 indicated by the arrangement of the constituents of the dolomite 

 around them. On weathering, the matrix is attacked first, leav- 

 ing the pebbles as rather prominent surface features. In one 

 instance the pebbles in the upper part of the conglomerate bed 

 were well rounded instead of being flat. The matrix of this bed 

 weathered to a yellow color. 



These conglomerates do not belong to the type described by 

 Grabau,^ for there is no evidence of any kind that the beds have 



*Grabau, A. W., "Principles of Stratigraphy," p. 530. 



