232 ASHLEY — GEOLOGY OF AEKA^;SAS. [May 13, 



in which this white material occurs does not appear to be constant. 

 In places it is a hard rock ringing under the hammer, with the 

 white specks sparsely scattered through it; in other places it is a 

 quartzite ; in some places the white and yellow specks occur in a 

 matrix of shining black rock; in others in a shaly breccia; but the 

 matrix is generally a light green earthy material. 



The proportion of white material varies from a very small per 

 cent, to rocks in which there is little else. In many of the harder 

 beds the soft white material weathers out, giving the rock a very 

 cellular appearance. A typical locality is on the Amity-Hot Springs 

 road a mile north of Amity. It here forms a bed thirty-three feet 

 thick. It appears to be regularly bedded at every exposure found. 

 It is well exposed in front of the Bushy Mill in 4 S., 30 W., sec- 

 tion 7, and on the Line road, in 5 S., 32 W., section i. It is 

 apparently but a short distance above the novaculite series. Wil- 

 liams and Penrose, of the Arkansas Survey,^ report a similar deposit in 

 north Arkansas, which there occurs on the dividing line between the 

 Silurian and Lower Carboniferous strata. The examinations which 

 they have made microscopically and otherwise have led to the sug- 

 gestion that this is an ash bed indicating volcanic activity some- 

 where at the end of the Silurian. The great variation in the matrix 

 rocks would seem to agree with such a theory.'^ 



Novaculite Breccia. — At the same locality a mile north of Amity 

 on the Amity-Hot Springs road are found many fragments of a 

 novaculite breccia. This is probably the same as the novaculite 

 conglomerate referred to by Mr. Griswold, but in this case it is 

 invariably a breccia, the fragments which here measure from an 

 inch or two in diameter down, presenting no evidence of previous 

 erosion. 



The matrix of this breccia is usually a light green sandstone, 

 though in a few instances it is reddish or brown. The fragments 

 which in some cases make up the bulk of the rock, in others only 

 scattered through the sandstone, are of novaculite and vary in color 

 from white to red or black. 



Changes in the Rocks. Sand a?id Clay. — The most universal 

 change is the disintegration of the rocks into sand and clay. Pos- 



'^Geol. Surv. of Ark., An. Rep. for 1890, Vol. ii, p. 375, and Vol. i, p. 128. 



2 Chemical analyses of the north Arkansas beds here referred to show that they 

 are phosphate rocks. An example of the rock collected by Dr. Ashley was 

 found to contain only nine per cent, of calcium phosphate. — J. C. Bi'anner. 



