1907. Seymour. — Geology of Lamb ay. 13 



xenolithic lava and an altered ash. The areas which appear 

 to the writer to consist of volcanic ash are indicated by a 

 special sign on the accompanying map, and include one or 

 two areas apparently regarded by Messrs. Gardiner and 

 Reynolds as consisting of xenolithic andesites. 



Some small veins of red jasper occur in the rocks forming 

 the high ground south by west of Harp Ear ; similar veins 

 are found also a few hundred yards south of Heath Hill. 

 I have received from Mr Baring a piece of red jasper which 

 he obtained in the rocks at the foot of the cliff south of the 

 Seal Hole. This material would therefore appear to be dis- 

 tributed over several parts of the island. 



A statement appears in a foot-note to the Geological Survey 

 Memoir to the effect that lumps of hematite were noticed on 

 a small knoll 200 yards S. W. of Ravens Well, and further 

 that " Professor Sullivan suspects that a copper lode may 

 here be present," i.e., at the mouth of Thorn Chase valley. 

 No traces of the first named mineral were discovered, but 

 minute crystals of iron pyrites were got in the rock at 

 Scotch Point, and some of the green staining of the limestone 

 at Kiln Point at its junction with the andesite may be due 

 to the presence of copper pyrites. 



References in Text. 



'1.) Du NoyER (G. V.) : Explanations to accompany sheets 102 and 112 



of the Maps of the Geological vSurvey of Ireland (1S61), 



pp. 46-50. 

 .2.) Hull (Edward) : On the Microscopic Structure of the Lainbay 



Porphyry, fourn. Roy. Geol. Soc. Ireland (1874) vol. xiv., 



p. 44. 

 (3.) LA.SAULX (Arnold VON) : Tscherm. Mm. u. Petrogr. Mitlh., Bd. i, 



(1878), p. 419. 

 (4.) Teall (J. J. H.) : British Petrography ('1888), p. 248. 

 (5.) CoeE (G. A. J.) : [Passing reference to Eambay]. Irish Naturalist, 



vol, i., p. 35 (1892). 

 (6.) Harker (Alfred) : Petrology for Students (1895), p. 106. 

 (7 ) Seymour (H. J.) : Excursion of Dublin Nat. Field Club to Lambay. 



Irish Naturalist (1896), vol. v., p. 1S6. [References to 



finds of flint cores and flakes]. 

 (8 ) Gardiner (C. I.) and S. H. Reynolds : The Bala Beds and Asso- 

 ciated Igneous Rocks of Eambay Island, Co, Dublin. 



Q. /. Geol. Soc. (1898), pp. 135-148. 

 (9.) Wright (W. B.) and H. B. Muff: On a Pre-glacial Raised Beach 



on the south coast of Ireland. Ptoc. Roy. Dub. Soc, 



vol. z. (n. s.), Part 2 (1904). 



