chap, xxx 
ICING’S COUNTY 
39 
disturbed close to the margin of the neck, sometimes dipping towards the 
volcanic centre, and sometimes striking at it. Among these strata a small 
neck of breccia, of which only a few square yards are visible, rises close o 
the edge of the bog that covers the adjacent part of the great plain 
The material which chiefly forms these necks is one of the rnos 
remarkable breccias anywhere to be found in the volcanic records ol t me 
British Isles The first feature noticeable in it is the pumiceous charactei 
of its component fragments. These consist of a pale bluish-grey basic 
pumice, and are generally about the size of a hazel-nut, but descend to 
mere microscopic dust, while sometimes exceeding a foot in length, iney 
are angular, subangular and rounded. Occasionally they stand ou as 
hollow shells on weathered surfaces, and in one instance I noted t ia ie 
vesicles were flattened and drawn out parallel to the surfaces of t ie s le , 
as if deformed by gyration, like a true bomb. 
The breccia remains singularly uniform in character throughout all 
tire necks. Its basic pumice presents much resemblance to that so charac- 
teristic of the Carboniferous necks of Scotland, Derbyshire and t ie s e o 
Man. The abundant vesicles are generally spherical, and as they have 
been filled with calcite or chlorite, they look like sma seeds scattered 
through a grey paste. Though I broke hundreds of the lapilli, I did 
uot notice among them any volcanic rock other than this pumice. 1 am 
not aware of any other neck so homogeneously filled up with one type of 
Pyroclastic material, and certainly there is no other example known m the 
British Isles of so large and uniform a mass of fragmentary pumme. 
Limestone fragments are not uncommon m this breccia. I iey - 
seinble the strata around the vents. Pieces of the adjacent cherts may 
also be observed. In one or two cases, the limestone fragments were found 
by me to have an exceptionally crystalline texture, which may possibLj 
indicate a certain degree of marmarosis, but on the whole there is little 
trace of alteration. . f 
The fragments of pumice in the breccia are bound together by a cement o 
calcite. In fact the rock is, so to speak, saturated with calcareous ma eria , 
which, besides filling up the interstices between the lapilli, has permeate 
the pumice and filled up such of its vesicles as are not occupied by some 
chloritic infiltration. . , • 
I did not observe unmistakable evidence that any part of the brec • 
is stratified and intercalated among the limestones, nor any vestige o 
ashy material in these limestones. But it is possible that traces of suci 
interstratification may occur in the low ground to the north-west o 
Lroghan Hill, which I did not examine. 
In only two places did I notice even a semblance of the intercalate 
of limestone in the breccia. One of these is at Gorteen, where a band oi 
limestone strata a few feet thick is underlain and overlain by breccia. 
though the superposition of the layers of finely stratified dark limestone and 
chert on the breccia is well seen and thoroughly defined, no lapilli or as y 
diaterial are to be seen in the limestone. Detached pieces of Sinn ar 
