412 



THE GEOLOGIST. 



tached and scattered masses of rock as tliey should the boulder-masses in the 

 drift.— Yours, &e., Geeat Yajimouth. ^ , „ , , v i 



EossiLS TROM GmvAN, Ayrshiue. — Sir,— I shall be obliged it you can give 

 me any information about the deposits in the immediate neighbourhood of Gir- 

 van, Ayrshu-e. Some fossils from a limestone-quarry there were sent me by a 

 friend. They appear to be a species of Euomphalus; but from the manner in 

 which they have been extracted from the quarry, only one side can be examined, 

 the other being embedded in the limestone. I should be much obliged if you 

 could inform me whether the limestone-deposits of Girvan belong to the moun- 

 tam-Kmestone or to the Silurian period. — Yours, &c., W. M. B. A._— In 1850 

 Sir Roderick Muxchison and Professor James Nicol devoted some time to the 

 examination of the Girvan neighbourhood, and the result was a memoir, 

 illustrated by a map, sections, and plates of fossils, in the Geological Society's 

 Journal (No. 27, vol. vii.) Prom this memoir we learn that the limestones at 

 Craighead, Assel Burn, Aldeans, Craigneil, and Bogang are of Lower Silurian 

 age ; and that the limestones south-east of Mullock Hm, and at Lemmy-laue 

 are Carboniferous. 



The Euomphalus-lookmg fossil may possibly be a Maclurea, which is 

 characteristically a Lower Silurian fossil, and is found near Girvan. 



Artificial Nodules : Yenus'-Hair Stone. — Sir,— I trust you wiR ex- 

 cuse my again troubling with a few small specimens, which I shall be ex- 

 tremely obliged if you wOl name. 



The shells were taken out of a kind of smooth, round nodule, composed of a 

 soft, sandy material of which I enclose a portion. It was brought to me lately, 

 having been purchased at Dover ; its appearance was extremely artificial, being 

 perfectly covered with small ammonites, shells, etc., embedded on the surface of 

 this sandy nodule. 



The small brooch of what is commonly called Yenus'-hair I enclose, because 

 T am anxious to know its composition. I have another larger specimen of 

 which the coloured streaks, running transversely through one side of the 

 crystal, are of a darkish brown colour, the crystal itself being perfectly clear, 

 Kke the pui-est glass. — Yours &c., W. M. B. A., Mid-Lothian. — The nodules 

 referred to are artificially made by mixing the dark green sand of the Upper 

 Greensand of Eastwear Bay, near Folkestone, with gum or glue. Immersion 

 in hot water will at once detect this fraud, for which one or two persons at 

 Dover are notorious. The fossils stuck on the outside are the commonest 

 Gault fossils obtained from Copt Point and Eastwear Bay, such as Ammonites 

 lautus, A. splendens, A. tuherculatiis, A. varicosus, Hamites attenuatus, Nucula 

 pectinata, N. ovata, Inoceramus sulcatus, I. concentricus, Dentalium decussatum, 

 D. ellipticum, &c. 



The fine long threads in brooch-stones, known as "Yenus'-hair" are usually 

 fibres of Asbestos or long acicular crystals of Titanium embedded in pure 

 crystalline quartz. The "Yenus'-hair" sometimes also consists of Actiiiolite 

 or Tremolite, but that in the brooch-stone forwarded to us we believe to be 

 Butile (Titanium). Professor Tennant has in his collection a magnificent mass 

 of pure quartz containing wire-like crystals of Titanium more than two inches 

 in length. 



Tertiary Strata West or Woolwich, at Peckham, &c. — After read- 

 ing in the July number of The Geologist the description of that interesting 

 section of the Tertiary strata exposed at Woolwich, many doubtless like myself 

 visited that locality and returned gratified. On thinking that it might be "^pos- 

 sible to trace that series inland or westwards, I concluded to try, and what Little 

 success I have met with may perhaps not be uninteresting to some of your 

 readers. After leaving Woolwich in that direction, the first traces of the s'heU- 

 bcd which I found were in the cuttings of the London, Brighton, and South- 



