408 



DALE— CAMBRIAN MANGANESE DEPOSITS OF [April 25, 



219 A 12 is a fissile green shale measuring 1.4 feet in thickness 

 with conspicuous black nodules which on weathering become white. 

 Because of the similarity in form and color with those of 219 B 5, 

 A 5, A II, and those to be described from the bed immediately above 

 this one, the suggestion is made here that these nodules also may be 

 phosphatic. 



219 A 13 is a phosphatic nodular manganiferous calcareous shale 

 bed, I foot thick^ with the nodules common in both bottom and top 

 portions of the bed (Fig. 29). The nodules because of their white 



Fig. 29. Photograph of a polished vertical section of a phosphatic nodu- 

 lar shale seam, 219 A13; natural size, a, phosphatic nodule; b, shale with 

 trilobite fragments. 



weathering and subspherical to elongated form resemble those of 219 

 A 12, A II, A 5, and B 5. In chemical composition the nodules of 

 this bed resemble those from the Cambrian of southern New Bruns- 



