44 
the carboniferous volcanoes 
HOOK VI 
Cherty limestone more than 
Decomposed green tuff 
Bluish-green, calcareous laminated tuff 
Limestone, slightly ashy 
Green tuff 
Fine-grained decomposed tuff 
Green tuff, obliquely laminated 
Fine laminated tuff 
Green compact tuff 
Obliquely laminated slialy tuff 
Concretionary ashy limestone 
Compact ashy limestone . 
Green shaly tuff, much weathered . 
Ashy limestone 
Compact green tuff more than 
20 feet 0 in. 
2 
4 
1 
0 
0 
1 
0 
1 
0 
1 
2 
0 
0 
4 
?) 
33 
33 
33 
33 
33 
33 
33 
77 
77 
77 
6 
0 
8 
2 
4 
7 
8 
8 
10 
4 
0 
77 
77 
77 
77 
77 
77 
77 
3 ) 
33 
33 
33 
33 
33 
33 
7 
0 
33 
33 
The tuffs which m the southern part of the basin underlie the less basic 
wTifth tV 11 T e reSp6CtS fr ° m th0SB which Mier north are associated 
with the Upper Limestones. They are green, sometimes dull purplish-red 
im y granular rocks, made up m large part of andesitic debris. They are 
h Hi °° S Vt Par C17StalS ’ minUte ’ aomewhat funded and subangular 
bled sLle Tho, 01 l SOme ^ ^ to ^r with bits of grit°and 
’ ' ‘ 10ll gh generally much decomposed, they are sometimes 
mp„ enough to be need for kuldihg-stone. Undei themicro^ th* 
tuffs ate seen to abound m andesite-lapilli, with a few pieces of felsitic rocks 
I " J" aU TV S6 ’ thr ° Ugh Which are scattered broken felspars and 
occasional vesicular lapilli. 1 
The tuffs around Limerick, iiiterbedded with the 
Black (Upper) Limestone, are distinguished by a scarcity 
of andesitic debris, by their persistent dull green ish-o-rey 
colour, and more particularly by the abundance of minute 
lapilli and larger fragments of an epidote-green, finely 
vesicular, easily sectile basic pumice. Under the micro- 
scope much of this material is found to be an altered 
basic glass of the nature of palagonite. These tuffs are 
m evident relation with the more basic lavas that 
accompany them. The manner in which they alternate 
with the black limestone shows that the conditions 
for the eruption of this more basic detritus continued 
to be very similar to those that existed when the ande- 
Fm. 193.— Section in ® itlc tuf,s were e Jected. As a good illustration of this 
quarry °n roadside east feature the accompanying section (Fie 19U 
of Limerick close to fmm n „ v. gl\ en 
viaduct of the Limerick r quarry on the side of the high-road between 
and Erris Railway. Limerick and Annacotty. The total depth of strata 
L re f es ented is about 15 feet. The black limestone 
or calcareous tuff. at the bottom is a tolerably pure calcareous rock. It 
is divided into bands by thin partings of a fine • i 
calcareous tuff, each marking a brief discharge of ashes & from some’ neUli- 
