Northern California and its peculiar Lawas. 47 
may be regarded: (1) as remnants of the rock from which the 
basalt may have been derived deep in the earth by fusion; (2) 
as inclusions picked up by the lava on its way to the surface 
at the time of the eruption; (8) as crystallizations from the 
magma itself; (4) as of secondary origin derived by the altera- 
tion of other minerals. 
The absolutely fresh unaltered condition of the basalt for- 
bids the belief that the quartz is of secondary origin and the 
character of the quartz is such as to render equally untenable 
the view which regards it asa remnant of the original rock 
from which the basalt may have been derived by fusion. So 
we have left to determine whether the quartz grains are inclu- 
sions or secretions. 
The fractures in the quartz grains and the border of glass 
and pyroxene by which they are surrounded have been con- 
sidered characteristic of quartz inclusions, but in fact such 
phenomena are equally common to some other minerals which 
are universally regarded as early secretions in the magma. The 
quartz always occurs without well defined crystallographic 
form in clear, vitreous, roundly-corroded grains just as in some 
of the more acid porphyritic rocks where all observers agree 
that it is indigenous to the lava. If the quartz grains are re- 
garded as inclusions and we consider their multitude we would 
expect to find a greater range in their size and in the kind of 
included material. Fragments of any other sort in the basalt 
have been diligently sought for in vain. ‘These considerations 
lend much support to the view which conceives the quartz to 
be an early secretion in the magma, but a more impressive 
argument in its favor is based upon the uniform distribution 
of the quartz grains throughout the entire mass of the lava 
including all its fragmental forms. It is as intimately inter- 
mingled with the other constituents of the basalt as the feld- 
spar and the olivine, only somewhat less abundantly. ‘To fully 
appreciate this fact the basalt must be examined in the field 
where it appears impossible to explain the omnipresence of the 
quartz satisfactorily on any other supposition than that it origi- 
nated in the magma itself. We must bear in mind also that 
this particular basalt was very viscous and stiff at the time of 
its eruption, so that it broke up and shoved along over the sur- 
face as a great pile of stones. On account of the high degree 
of viscosity, inclusions would be found only in the basalt 
which came up very close to the side of the volcanic chimney 
and they would not spread into other parts of the lava. Of 
this I was fully convinced by an examination of the volcanic 
necks near Mt. Taylor in New Mexico. They are of basalt, 
which at the time of its eruption was apparently more liquid 
than that containing the quartz at the Cinder Cone near Snag 
/ 
