Varwlitic Pillow-Lava. — Daly. 77 
facts stated in the paragraphs quoted seem, on the contrary, 
to point to the correctness of Teall's position. Teall doubtless 
meant that the detailed surface of the lava-pillows is more like 
that assumed by pahoehoe than like the ragged surface of aa 
blocks, a fact which is fully corroborated in the Newfoundland 
occurrence. ( See Plate XV, Fig. 4. ) In other respects certain- 
ly well recognized by Teall, pillow-lava is closely allied to the 
aa form. The conspicuous absence of rugosites in the pillows 
produced from lava welling out and rolling up into ellipsoids 
may be inherent in the nature of submarine aa flows. At any 
rate, it is in the highest degree probable that a smooth, often 
ropy, surface is impressed on the lower blocks overridden by an 
aa lava-flow. The great bulk of the units in a pillow-deposit 
must be compared with such blocks moulded by the weight of 
heavy overriding blocks rather than with the extremely cracked 
and rough blocks at the surface of a terrestrial lava-flow. The 
already well recognized common association of pillow-lavas 
with radiolarian cherts and with other contemporaneous ma- 
rine sediments occurring above and below, and within the in- 
terstices of, a pillow-deposit, forms a strong argument in 
favor of Teall's view. At all of the Newfoundland localities, 
the lava is overlain and underlain by conformable argillitic 
and arenaceous strata which are without doubt the result of 
sedimentation in fairly deep water. The deposition seems to 
have been discontinuous only by virtue of the short-lived, rapid 
out-flow of lava on the sea-floor. That the Newfoundland lava 
is not intrusive into loose bottom silts in this particular in- 
stance* is shown by the apparently complete absence of argil- 
laceous material such as would be expected to become incor- 
porated in the mass between and within the pillows as the lat- 
ter would be rudely rolled and thrust through the silt. On 
that supposition, moreover, it would be difficult to explain the 
existence of the highly vesicular, continuous lava-flow under- 
lying the whole pillow-deposit. 
Conclusion. — The writer has therefore concluded that, 
on the best working hypothesis, the Newfoundland rock 
.s the product of the extrusion of basic lava into sea-water of 
some depth. That view is confirmed by Russell's recent dis- 
* Cf. experiment by Johnston-Lavis, South Italian Volcanoes, Naples, 
1891, p. 42. 
