I5Q KANSAS UNIVERsnV Ol' AR'll'.KLV. ■ . 



Theories of Formaiion. -With tlie coal miners of this and 

 otlier states different theories liave been advanced to account for 

 thfc? existence of clay seams. One of these theories is that the 

 fissures represent former underground waterways, and that the 

 clay represents silt or sediment of various kinds which the stream 

 deposited in its course, such deposition having been continued 

 until the whole space of the fissure was filled. But how the fissure 

 was produced in the first place this theory does not say. Another 

 theory expressed by different miners is that the clay seams were 

 formed contemporaneously with the coal, Neither of these views 

 seems to correspond with all of the observed facts, consequently it 

 cannot be concluded that either of them is correct. Before giving 

 the, view of the writer let us glance hurriedly once more at the con- 

 ditions actually observed. 



OJ3SERVED Phenomena. After examining a large number of 

 mines and strip pit workings in the southeastern part of the state 

 where the "clay veins" are quite numerous, the following facts 

 there observed may be summarized: 



1. The walls of the clay-filled fissures present a rough frac- 

 tured surface as if they had been broken and torn apart by a hor- 

 izontal stretching process which was greater than the coal seams 

 could endtire. In some cases the layers of coal are pressed up- 

 wards near the upper surface and downwards near the lower. 



Fig- 3- 



2. There is always an upward displacement of the shale seams 

 at the upper extremities of the "clay vein." Displacement, 

 especially in the coal, is attended by fracturing. Fig. 4. 



3. The fire cla}' in the fissure is usually homogeneous and 

 structureless, but sometimes has an approach towards a lenticular 

 structure. In all cases the clay in the "clay veins" is similar to 

 that underlying the coal, and when the latter is composed of two 

 or more varieties, as a dark and a light one, the same relation 

 exists between them in the clay vein, as is shown in Fig. 5. 



4. Angular pieces of coal are often found mixed through the 

 clay in the fissure. These are evidently fragments of the original 

 coal bed, for in many places their exact former position can read- 

 ily be determined by their shape and the appearance of the wall of 

 the coal. There is very little broken or finely powdered coal to be 

 iound in any of the clay seams. 



Probaule Origin. — It would seem to the writer that there is no 

 room for doubt regarding the origin of these "clay veins." Long 

 after the coal was formed and consolidated almost to its present 

 state, vibratory movements of one Jcind or another fissured the 



