220 



EDWARD C. JEFFREY 



geological ages in different parts of the world. The writer has 

 examined coals derived from regions as far apart as Alaska and 

 Patagonia, Dakota and Texas, Washington and Virginia, Great 

 Britain and Japan, Sweden and Tasmania in geographical separa- 

 tion, and in stratigraphic distribution from the Devonian to the 

 Miocene and the present epoch. The results of these investiga- 

 tions have been satisfactorily uniform. We are now apparently 

 in the position to judge of the great problems of coal formation 

 from the all-important aspect of the organization of the coal 



Fig. I 



Fig. 2 



itself. In other words, we are no longer compelled to infer the 

 nature of coal from the conditions of deposit of the surrounding 

 strata, which may have been laid down under very different circum- 

 stances, but we can reach definite conclusions from the structures 

 revealed by the coal itself under the microscope. 



Reference has already been made to the fact that certain coals, 

 containing large quantities of spores, are generally admitted to 

 have been formed, not on land as the case with peat, but as sedi- 

 mentary deposits in open water. Fig. i illustrates a notable car- 

 bonaceous deposit of this type, namely tasmanite. In the upper 

 part of the figure one spore still retains its rounded contour, but 

 the spore'material as a whole, which is very abundant, is represented 

 by the collapsed spore coats, inclosing a linear cavity. Fig. 2 

 shows the^structure of another type of spore coal, an oilshale from 



