708 TRANSACTIONS OF SECTION C. 



overlapped by this cast, is the cast of a smaller footprint, similar m form but o!ily 

 4 cm. in its greatest length ; this may represent the footprint of a still smaller 

 creature, or may be the cast of the manus of the same one. In both cases the 

 impression is deepest at the heel, that of the iii-st being 2'5 cm. deep and the 

 second 2 cm. There seems to be no trace of webbing. As far as I have been 

 able to ascertain, no footprints of this kind have been found in the lower oolite 

 of England, and I am unable to find any reference to such a find in any other 

 part of the world. 



9, Sixth Report oti the Fauna and Flora of the I'rias of th^ 

 British Isles. — See Reports, p. 269, 



10. Report on the Faunal Succession in the Carboniferous Limestone 

 (Avonian) of the British Isles. — See Reports, p. 267. 



11. D op pier ite from Sluggari, Bog, Co. Antrim. By R. Welch. 



This curious jelly-like substance was discovered in a co. Antrim bog by Mr. 

 Robert Bell, of the Belfast Naturalists' Field Club, a few years ago. The bog is 

 an old cutaway one, and was formerly about 11 feet deeper than at present. The 

 dopplerite occurred as a vein about 3 inches thick about 7 feet from present 

 surface, in the black dense lower peat. It is very slightly elastic under pressure, 

 but breaks away with a jet-like fracture under tension. It contracts very much 

 in drying, and becomes much like jet in colour, fracture, and lustre. Irish 

 observers in the past have noted a jet-like substance in peat without recognising 

 what it was, but Mr. R. Moss, the secretary cf the lloyal Dublin Society, did so 

 when the first specimens found by Mr. Bell were sent to liim. Mr. Moss, in an 

 ^•ticle in ' The Irish Naturalist' for August 1003, states that it contains in the 

 dry state about 70 to 73 per cent, of humic acid, and that may be regarded as the 

 nearest approach to humic acid occurring in Nature. Since this appeared I have 

 found it in a bog near Cookstown, co. Tyrone, where the peats cut from the turf 

 saturated with dopplerite dry almost as hard as a brick. It is perhaps much more 

 common than is supposed, but is probably seldom separated out in such thick masses 

 as Mr. Bell finds in Sluggan Bog. Mr. Arthur Stelfox, another member of the 

 Belfast Naturalists' Field Club, has noticed it ii the West of Ireland. It was first 

 discovered in Germany by Herr Doppler, an inspector of wines, about fifty years ago, 



TUESDAY, SEPTEMBER 8. 

 Discussion on Jfountain Building. 



Professor J. Jolt said : Of the many featuies which recent investigations into 

 mountain structure had revealed, the overlap of the upper recumbent folds upon 

 the lower in such a way that the uppermost folds were of greater span than those 

 beneath, was one of the most characteristic and at the same time one of the most 

 difficult of explanation upon existing views. Ihe notion that a horst (or horsts) 

 might be responsible for such a structural feature laboured under the objection 

 that at the depths at which we must suppose the horst located, the temperature 

 must be almost certainly one at which siliceous rock-masses would be highly 

 viscous and not capable of playing the part assigned. 



However, an explanation of the phenomenon appeared to reside in this very 

 condition of viscosity, for it would follow that, upon the first developmeiit of 

 folding, those synclinal parts of the folds which became depressed into the zone of 



