408 E. E. L. Dixon— The Gavaniie Overthrust. 



and denudation to the extent of 8,000 feet over the anticlinal axis, 

 were accomplished after the deposition of the Lower and before the 

 beginning of the Upper Old Red. The surface on which the Upper 

 Old Red rests, in Forfarshire, is broadly horizontal, but very uneven — 

 evidently an old land-surface. 



PAPERS REFERRED TO. 



Barrow, G. " Supposed Silui-ian Rocks on the South-Eastern Border of the Scottish 



Highlands " : Q.J.G.S., vol. Ivii (1901), pp. 328-45. 

 Evans, J. W. " The Geology of the North-East of Caithness." London : Green, 



McAllan, & Fielden. 1891. 

 Geikie, Sir A. "The Geology of Central and "Western Fife and Kinross" : Mems. 



Geol. Surv. Scot., 1900. 

 Home, J. "Recent Advances in Scottish Geology" (Pres. Addr., Sect. C, 



Brit. Ass.) : Geol. Mag., Dec. IV, Vol. VIII (1901), pp. 4.52-70. 

 Macnair, P., & Raid, J. "On the Physical Conditions under which the Old Red 



Sandstone of Scotland was deposited " : Geol. Mag., Dec. IV, Vol. Ill (1896), 



pp. 106-16. 

 Murchison, Sir R. I. " Succession of the Older Rocks in the Northernmost Counties 



of Scotland " : Q.J.G.S., vol. xv (1859), pp. 353-418. 

 Powrie, J. "On the Old Red Sandstone Rocks of Forfarshire": Q.J.G.S., 



vol. xvii (1861), pp. 534-42. 

 Salter, J. W. " On the Upper Old Red Sandstone and Upper Devonian Rocks " : 



Q.J.G.S., vol. .\ix (1863), pp. 474-96. 



EXPLANATION OF PLATE XX. 



Fig. 1. — Photograph showing horizontal Upper Old Red conglomerate resting 

 against inclined surface of Lower Old Red. The full dip of latter beds 

 is not seen. The lower part of the Upper Old Red on the left consists of 

 soft sandstone. Clifi 200 yards east of Whiting Ness. Height of cliff 

 about 50 feet. 



Fig. 2. — Upper Old Red (on right) faulted down against Lower (on left) at Dark 

 Cave, Seaton Point. Height of cliff at fault, 140 feet. At the extreme 

 point the inclined beds of the Lower series are seen rising from under the 

 Upper. On the other side of the Point the junction may be seen to be 

 similar to that in Fig. 1. 



EXPLANATION OF PLATE XXI. 



Fig. 3.— Photograph of Upper Old Red conglomerate at Cove Haven, Seaton Bay. 



Height of cliff in photo about 10 feet. 

 Fig. 4. — Cliffs at Cove Haven, Seaton Bay, sho^ving general character of Upper Old 



Red of this outlier. Height of cliff in foreground about 50 feet. 



III. — The Gavarnie Overthkust, and other Problems in Pyrenean 



Geology. 



By E. E. L. Dixox, B.Sc, F.G.S. 

 {Concluded from the Avgust Number, p. 373.) 



OF the places where undisturbed limestone rested on older rocks, the 

 most important visited by us was the valley of Hount-Sainte on 

 the Spanish slope. This does not appear to have been considered by 

 Carez, nor to have been hitherto described in detail. The following 

 sequence is clearly exposed, in descending order : — 



4. Palaeozoic — Devonian and Carboniferous according to Bresson. 

 Shales and limestone in the lowest part, the base evidently a plane 

 of disturbance. 



