3'2± The American Geologist. November, 1894 
and was the fragment from the lower member of the San 
Francisco sandstone V 
3. The bounding surfaces are perfectly sharp and definite 
■•and entirely enclose each separate spheroid." It may be 
questioned whether flowage could thus entirely separate them 
from each other, for there seems to be no exception to their 
individual isolation. This rather indicates an individual his- 
tory for each mass, involving separation from some parent 
mass, transportation to its present position and consolidation 
with its neighbors under the action of some later cementing 
agency. Had flowage produced these spheroids it is impossi- 
ble that they would not somewhere show gradations into each 
other and finally into a simple lava sheet where they would be 
less and less distinct ; the mass of the rock in general could 
not have so flowed everywhere in so uniform and yet so pecul- 
iar a fashion. 
4. Judging from the descriptions the spheroidal basalt is 
not essentially different from the p3 T roclastic layer which 
overlies it. It seems to be allowable to suppose that they had 
a common origin, viz., as volcanic ejectamenta, the coarser 
bombs appearing in great profusion at the first eruption of 
the volcano, and the finer tuffs falling later. The lack of 
stratification in these deposits characteristic of oceanic agency 
may be due to the rapidity of the accumulation and the shel- 
tered location of the volcanic area to the eastward of the vent 
where waves and currents could not readily act upon the de- 
bris, or it may be due to the fact that the debris fell upon a 
land surface instead of into the ocean, as presumed by Mr. 
Ransome. It is hardly possible, however, that at that place 
some of these materials, whether bombs or tuffs, should not 
have fallen into the ocean, and if the jaspers were deposited 
in the ocean on the eastern side of Point Bonita, as shown 
by their being embraced in the fragmental San Francisco 
sandstone, the tuffs at least may have fallen into the ocean 
over a large area and mingled with, or entirety displaced, the 
usual accumulation of that sandstone. If the phenomena here 
are comparable with the features that have been described in 
the greenstones of Minnesota, jasperoidal accumulations will 
be found intimately mingled with the tuffs and also closely 
