Reports & Proceedings— Geological Society of Glasgow. 2389 
States, tourmaline is found more or less completely altered to a mica 
(probably phlogopite) and limonite, the degree of alteration decreasing 
with increasing depth from the surface, suggesting that the change 
was caused by the percolation of water from above. The freshness of 
tourmaline grains in sands is very probably due to the removal of 
the altered products by chemical and mechanical means. 
Il1.—Gzrotoeican Socrrry or Guascow. 
Votcanozs in AyrsHire.—At a meeting of the Geological Society 
of Glasgow, held on March 9, Mr. G. V. Wilson, H.M. Geological 
Survey, read ‘‘ Preliminary Notes on the Volcanic Necks of North- 
West Ayrshire’’. The area dealt with lies between Dalry, Ardrossan, 
and Largs, and has been found to contain the remnants of about thirty 
voleanoes. ‘The various necks were described, and it was pointed out 
that they were not all of the same age. While some are probably of 
Caleiferous Sandstone age and connected with the great Misty Law 
volcano further north, others were much later as they contained large 
blocks of sedimentary rocks, including one with a coal-seam which 
was large enough to be worked within the vent many years ago. 
This vent must therefore have been in action after the formation of 
the coals of early Carboniferous times. Fragments of charred wood 
also occurred, while in one instance sea-shells, which had evidently 
been washed from the sea-floor directly into the voleano, were found. 
This showed that the volcano had been either submarine or on low 
ground liable to submergence, and the shells being of a type not later 
than Millstone Grit, the age of the vent was approximately fixed 
thereby. It was pointed out that the ash in the necks was, in some 
instances, very similar to that which replaces the black-band ironstone 
over much of the Dalry district, which suggested that it had come 
from this source, and that activity had continued intermittently until 
Millstone Grit or later times. It was suggested that in the days of 
its activity this district had resembled the San Franciscan volcanic 
field of Arizona. The paper was illustrated by a series of photo- 
micrographs and views. 
Mr. J. V. Harrison, B.Sc., described a section at Tormore, Arran, 
showing the junction of the two red rock series of Arran, and where 
no sharp line of division was visible. 
CORRESPON DEHN CE. 
> 
THE GRAINSGILL GREISEN OF CARROCK FELL. 
Srr,—Among a collection sent to me last year of small specimens 
from various well-known rocks in the British Isles was one of the 
-Grainsgill Greisen, Carrock Fell, described in vol. li of the Q.J.G.S. 
by Mr. A. Harker. For purposes of comparison with local rocks 
I have had three sections prepared from this specimen, which was 
only about 14in. square and } in. thick, and used the remainder for 
separations in heavy liquids. The quantity of rock available was so 
