1867.] 



TIMIN^S — MALYEEN HILLS. 



359 



XXXYII. Bedded rock, south of the cave, near the footpath ; con- 

 tains a few grains of olivine, and a little quartz in cavities. Parts 

 of this rock resemble the matrix of the lava of the Capo di Bove, 

 near Rome. In its chemical composition it nearly corresponds with 

 that which Bunsen gives for the "IS'ormal augite" of Iceland. Not- 

 withstanding its occurrence in regular beds, its mineralogical cha- 

 racter and its chemical composition make it probable that it has 

 jlowed over the surface. 0=2-923. 



XXXYIII. Bedded trappean rock, east of the ridge north of the 

 cave. It contains a few minute angular fragments of silica. 

 G=3-101. 



XXXIX. Over Castle Morton Common. Red rock, including a 

 few fragments of altered shale, minute quadrangular crystals of 

 felspar, and epidote, near a trap-dyke. Its chemical composition is 

 similar to that of some recent lava from Efrahvols, Iceland, analyzed 

 by Oenth. 



5. Sandstones more or less altered, consisting of trappean ash, in- 

 timately mixed with grains of quartz and felspar derived from the 

 disintegration of older rocks. These may be well observed on the 

 north of the ridge on which the cave is situated, where they are 

 associated with beds of trappean ash (XXXYIII.), of which they 

 are partly composed, and into which they appear to pass. In other 

 places the quartzose and trappean fragments are more or less segre- 

 gated ; so that in the same specimen one analysis will show nearly 

 all to be silica, a second nearly all trap, and a third a uniform 

 mixture of the two. Sometimes the quartz grains are so distinct as 

 to give the altered rock the appearance of quartzite, but are, not- 

 withstanding, intimately mixed with the basic elements of the tr^p. 











i 















cS 



^^ 



'^H 2 





d 





m 





JC 



"a 



o 



S2 



<U -CD 



6 



g 



1 



§1 



Jt 

 1— 1 1— 1 





XL. 



70-36 



13-07 



4-76 



0-15 



5-18 



1-96 



2-30 



2-22 



XL. Altered sandstone. Near the ridge north of the cave ; not 

 far from XXXYIII. 0=2-637. 



6. To the eastward of the trappean sandstones, commencing from 

 fifty to a hundred yards below them, are the compact-bedded f el- 

 stones of the large eastern buttress, the " fine-grained felspathic 

 trap " of Professor Phillips. The chemical composition of all these 

 rocks, so far as I have ascertained it, corresponds with that of the 

 " felstones " contemporaneous with the '' Cambro-Silurian " rocks of 

 "Wicklow, Wexford, Waterford, Kerry, and Caernarvon, as deter- 

 mined by Professor Haughton ; but they have less alkali, and pro- 

 portionally more lime. They also resemble those rocks in some of 

 their physical characters, and in their association with beds of 

 " greenstone ash." Lower down, towards the east, near the base 

 of the large buttress, the rock is a petrosilex, of which the composi- 



