392 



THE GEOLOGIST. 



in the outer concentric laminated layers of still unliardened mud encircling 

 tliem. I can bring evidence to show that this is no effect of disintegration ; 

 and I am anxious to know how far the laws respecting chemical segregation 

 under conditions such as described are ascertained, or if any relation can be 

 traced between such facts and the well-known phenomena of slaty cleavage— 

 the twisting, as it were, of gneiss round the granitic centres of mountains, and 

 the contortions in various rocks hitherto erroneously ascribed to violent squeez- 

 ing, &c. The manner in which water enters and leaves a given substance may 

 ultimately produce a change of form, just as electiic currents passed through 

 iron render it different from its former state. I have observed that where the 

 s ibstance acted upon is a stationary mass of mud or sand, the layers all follow 

 one direction, until we come to a sort of axis, as it were, and there the direc- 

 tion of the laminae become reversed. 



Now if the crystalline arrangement of bodies depend upon the weight of 

 their atoms, and that the medium in which they are placed, as well as the 

 motions to which they are subjected must be studied to produce artificial crys- 

 tals, why should chemists not be able to elucidate the law^s by which large 

 masses not only have an internal minute crystalline structure, but also a regular 

 geometric arrangement into larger squares or circles, both these effects being- 

 produced by the force of gravitation. Were it proved that the lamellar struc- 

 ture of rocks owes its origin to water, it would be an additional evidence that 

 granitic rocks are in reality not of igneous origin. — Yours, &c.. A., Belfast. 



Manufacture of Stone Implements. — Sm, — The stone axes such as your 

 " Inquirer" describes having doubtless excited mach interesting speculation, 

 it is to be hoped your next number will contain replies to some of his queries 

 regarding implements which seem to have been manufactured by people singu- 

 larly endowed with the virtue called patience. Perhaps the author of the paper 

 on the " Giant's Causeway," which appeared some time ago in your magazine, 

 being an antiquarian as well as a geologist, would give some suggestions 

 regarding their manufacture ? 



I have seen one, belonging to Lord Talbot de Malahide, the careful work- 

 manship and high fmish of which might well call forth similar inquiries to 

 those of your correspondent. It was, as nearly as I can recollect, formed of 

 basalt also ; and being so well finished suggested the use of a metal in its 

 manufacture, which, however, may have been too scarce to have superseded the 

 use of stone- weapons. 



Stones along a sea-beach are often perforated by marine creatures, so that 

 handles could easily be adapted to them, but then they are always composed of 

 limestone, a rock which I have never known to be used for these stone axes. — • 

 A. B. W., F.G.S. Sept. 8th, 1860. 



Lias at Whitchurch. — Sir, — In the geological map that accompanies the 

 last edition (the 3rd) of Sir B. Murchison's " Siluria" I observe a patch of 

 Lias marked as occurring between Whitchurch and Market Drayton. 



I should be glad to know whether on that patch there be any accessible sec- 

 tions whence might be procured specimens of the very interesting fossils of the 

 Lias formation. Being a new* comer to the neighbourhood, and moreover a 

 very tyro in geological studies, I, on both these grounds, stand in need of a 

 little help in the way of information. — Faithfully yours. Omega. 

 P.S. Arc there any geologists in this locality or neighbourhood ? 

 Pish from the Coal-Measures. — Sir, — You will oblige me by informing 

 me in your next number which is the best work that treats of the fish of the 

 Coal-measures next to Agassiz's " Poissons Possiles." — Subscriber. 



The fossil fish of the Carboniferous rocks are not yet fully described. 

 IVyond some scattered notices by Egerton (in the Geol. Quart. Jour.) and 

 others, there are no other descriptions except those in Agassiz's great work. 



