366 The American Geologist. » June, 1892 
been accustomed. They show that this rock was not a congealed 
plutonic mass, for sucha mass could not acquire an amygdaloidal 
structure, except when it becomes volcanic. It is only when 
there is a sudden release of surrounding pressure that the con- 
fined gases of igneous rocks gain relief from their confinement, 
or that some of the confined substances manifest their volatility, 
forming scorie and amygdaloids. Was the element into which 
these were ejected, and which caused the rapid escape of gases, 
and then their rapid solidification, simply atmospheric air or was 
it oceanic water? If it had been atmospheric air then the sur- 
rounding rock, viz., the whole of the greenstone of the region was 
also ejected simply into atmospheric air and solidified under sim- 
ply atmospheric conditions. Not having been since submerged, 
at least not having been since rewrought, it would have in that 
case to show not only many evidences of perfect igneous or 
‘‘diabasic” structure, but it would have to exhibit about the same 
variations—barring the effect of greater time—as to stratification, 
texture, composition, etc., as can be seen in volcanic rocks of 
recent or Tertiary time. It could hardly shade off into the evi- 
dently sedimentary rock, having very nearly the same aggregate: 
composition, seen but a short distance further north along the 
shore of Long lake, and it could hardly constitute a belt from 5 
to 10 or 15 miles in width, lying always in the same stratigraphic 
position in the Archzean, and running, in accord with the strike of 
the rest of the Archeean, as well as substantially with that of the 
Taconic (which admittedly are governed by continental increments 
as the oceanic areas receded) for a distance of one hundred and 
fifty miles. 
If on the other hand these bombs, torn from some portion of 
the already hardened super-crust by the loosening action of vol- 
canoes, were hurled first into the air and fell into the ocean, all 
the structural, as well as all the microscopic characters which 
have been mentioned, might have been the result. The forma- 
tion in which they are found would be amenable, as it is, to the 
geographic distribution and stratigraphic position which all oceanic 
formations are found to possess. They would have been buried 
along with other finer voleanic ash and cinder in the waters of a 
hot or tepid ocean. Such waters would rapidly destroy the 
characters of the usual minerals found in volcanic ejections. 
There would result secondary minerals, such as chlorite, sericite, 
