J. 8. Newberry—Parallelism of Coal Seams. 367 
tion 
Prairie, however, the treelessness is probably produced by a 
contrary condition, viz: the extreme wetness of these lower level 
spois in winter. Here, therefore, the weeds and ferns hold and 
preserve the mounds, not only as the better sort, but also as the 
rier spots, 
When once attention is turned to the subject, the same 
henomenon in a less degree is observed in nearly all the tree- 
ess regions of California and Oregon, which have not yet been 
touched by the plough. On returning from Oregon, I observed 
it in the upper part of the Sacramento valley, where, however, 
the mounds are so small and inconspicuous as to escape obser- 
vation unless attention has been previously awakened—only a 
light dappling of the surface of the country. Similar mounds, 
more conspicuous than the last mentioned, but far less so than 
these of Oregon and Washington, under the name of “ho 
wallow” are well known to exist over wide areas in middle and 
southern California. They dapple the whole surface of the 
eastern portion of the San Joaquin and Tulare Plains, and are 
found also in the country about Los Angeles. The smaller, some- 
mes scarcely noticeable mounds of California, graduate com- 
pletely into the larger and more perfect ones of eastern Oregon, 
and these again into the still more perfect ones of M ) nd 
Prairie. If the mounds of Mound Prairie were an unique 
phenomenon, we might resort to exceptional modes of origin; 
but a phenomenon so wide spread must be attributed to the 
action of a wide-spread agent. 
Oakland, Cal., Dec. 15th, 1873. 
Arr. XXX.—On the Parallelism of Coal Seams; by J. S. 
NEWBERRY. 
IN the first volume of the Final Report of the Geological 
Survey of Ohio, Professor E. B. Andrews advances a theory 
to the successive deposition of coal strata which, if 
Permitted to go unquestioned, might seem to commit the other 
members of the geological corps to its approval. whereas, as a 
matter of fact, Prof, Andrews stands quite alone in its support. 
Very briefly, his theory is this: Ist, That coal-seams have accu- 
mulated in marshes along the sea shore, and therefore at or 
near the water-level; 2d, That the subsidences by which sev- 
eral coal seams were successively formed and buried were conti- 
nental and general; and 3d, That the coal-beds—from their mode 
