272 
TIIR GEOLOGIST. 
Nvitli it, and hcucc the coatiiii^ oC suljjliate of lime, for which I was tolally 
unable to account, until Dr. Bowcrbank was kind enough to impart to nic some 
of the vast information lie has amassed on the nature and iiabits of sponges, 
recent and fossil. — W. B. Kkstevan, Upper Hollov ay. 
On the Vertical Veins of Dark Limestone in IIed Shale at 
Templemore. — Dear Sir, — Permit nie to oilVr an explauation for the occur- 
rence of those " irregular vertical veins or thin dykes of dark grey compost 
limestone, which cross n nearly horizontal bed of reel shale near the base of the 
old red sandstone of the neighbourhood of Templemore," to whicli attention 
has been directed by your correspondent A. B. W., in the April number of 
" The Geologist." 
Let us suppose that the accompanying diagram^ fig. 1, represents the face of 
this bed. 
Lign. 1. — a, Sandstone ; i, Shale ; c c, Limestone mud filling up Assures ; d e, Limit of 
denudation. 
After the deposition of the shale and while it was yet in the state of mud, 
the sea bottom at this place became suddenly elevated above the waters, and 
subjected to rapid dcssieat ion, wliieh produced numerous cracks and fissures 
over its surface ; and these after a time were doubtless increased in dimensions 
by sxdjsequent atmospheric action. The land was then submerged ; but during 
the interval of this upheaval and dessicatiou, the sea around this particular 
area had ceased to deposit ferrugio-argillaceous mud as well as sand, owing, 
doubtless, to local changes of currents, the result possibly of those movements 
in the land which I have just supposed. Its sediment now consisted entirely 
of such highly calcareous materials as would be ca[)able of forming limestone 
only, and this, of course, filled up these cracks and fissures, and any other irre- 
gularities which existed over what was then the bottom of the sea. 
It is remarkable that in the neighbourhood of Templemore absolute beds of 
pure dark grey limestone are frequently found interstratified with the old red 
sandstones, and we may therefore rationally suppose that the shale which I am 
describing may have been at one time eovei'ed oy a bed of sueh limestone as I 
have alluded to, at which period of its history the section at this locality may 
have been tiiat which I have represented in the diagram fig. 2. 
After a time, the calcareous mud not only ceased to be deposited here, but 
another great and material change took place in the relative distribution of 
land and water. The sea bottom became sufficiently elevated to be brought 
