106 Major-Gen. McMahon — Culm-measures at Bude, Cornwall. 



PLATE V. 



Fig. 1. Spirifera? 



,, 2, 2a. Rhynchonella pugnus, Martin, sp. 



,, 3. Rhynchonella cuboides, J. de C. Sby., sp. 



,, 4. Goniatites, sp. near to G. rotatorius, de Kon. ? 



,, 5. Goniatites, sp. (section in limestone). 



,, 6. Chonetes ? sp. 



,, 7, la. Strophalosia Clarkei ; dorsal valves. 



,, 8. Strophalosia Clarkei?, ventral valve. 



,, 9. Aviculopecten tenuicollis, Dana, sp. 



,, 10, 10«. Goniatites micromphalus, Morris, sp. 



,, 11. Spirifera Kimberleyensis, sp. nov. 



„ 12. Spirifera Musakhey 'I 'en sis? Davidson, var. Australis, var. nov. 



[All the figures are of natural size, except where otherwise stated.] 

 (To be continued in our next Number.) 



II. — Notes on the Culm-measures at Bude, North Cornwall. 

 By Major-General C. A. McMahon, F.G.S. 



DURING a residence of six weeks at Bude, in the autumn of 

 1889, I enjoyed the opportunity of studying the Culm-measures 

 exposed in the bold cliffs of that part of the coast of Cornwall. 

 I know of no easily accessible place where the flexures and con- 

 tortions into which strata have been thrown by earth-movements 

 can be studied with greater advantage. Between Bude-haven and 

 Menachurch Point, a distance of one mile as the crow flies, there 

 are at least eleven synclinal and as many anticlinal folds, presenting 

 a variety of flexures of considerable interest to the geological 

 student. At one place a sharp fold in the shape of the letter an 

 placed on its side, complicated by slight rupturing, has resulted in 

 perpendicular beds being faulted in between strata dipping at a 

 moderate angle in a common direction ; whilst, at another place, 

 a similar flexure has led to vertical strata being jammed in between 

 beds dipping towards each other at a low angle. In some places 

 the contortions and convolutions are too complicated for verbal 

 description. 



Menachurch Point itself presents several features of interest. 

 The small headland that runs out from the cliffs and constitutes the 

 " point " coincides with a small anticlinal flexure faulted along its 

 apex. The smooth sides of the sharply-folded beds seem to have 

 allowed the waves to slide over them without sustaining damage 

 from the collision ; whilst the fault itself, giving an advantage to 

 the sea, enabled it to scoop out a deep cave at the very apex of 

 the Point. The roof and walls of the cave are, for the most 

 part, formed by one of the folded beds, and the fault caused by 

 the rupturing of the strata along the axis of the fold is here seen 

 at its minimum. As one mounts the ridge forming the headland, 

 however, and rises to a level with the top of the cliffs, the throw of 

 the fault gradually becomes greater, and the rupture between the 

 beds on the two sides of the fold increases until, at last, one finds 

 almost level strata faulted against nearly vertical beds. Unless one 

 had traced the discordance between the two sides of the flexure step 



