HUGHES : IXGLEBOROUGH. 
259 
used them with such admirable results as zonal indices in the 
Bristol area. This section had been measured ofT by Dr. Lloyd 
Morgan and Mr. Stoddart each in his own wsiy, but the corals 
and brachiopods are so well developed there, as indeed in most 
limestone areas of this age, that they are taken as the most 
convenient basis for the construction of the local vernier.* 
I did not re- open the question of the glacial originf of these 
beds, though its interest is revived by the discovery in so many 
parts of the world of conglomerates which appear to point to 
the local recurrence of glacial conditions throughout the whole 
of the geological series. To those who refer glacial phenomena 
chiefly to geographical changes this seems to be inevitable, 
but each case must be considered independently, and in that of 
oui' Yorkshire Basement Bed the evidence seems to be decidedly 
adverse to the view that the boulders owe their striae to the 
action of ice. 
The Structure of the Mountain Limestone. 
Xow we have to examine the new group in greater detail, 
and very curious are the phenomena presented. All of a sudden, 
above the basement bed, there succeeds a vast deposit of lime- 
stone. There has been nothing like it before in all the tens of 
thousands of feet of sediment which we see exposed below it all 
round. The Coniston Limestone, the only one we have in the 
district within sight, and the Gurrey Fach Limestone at a some- 
what lower horizon in South Wales are thin, impure, earthy, 
impersistent beds. But in the Mountain Limestone of Ingle - 
borough we find about 600 feet of almost pure carbonate of 
* Cf. Cosmo Johns and Vaughan, Geol. Mag., Vol. III., 1906, p. 320. 
Garwood ib., Vol. IV., 1907, p. 70. See also the papers by Dr. Marr and 
Professor Garwood, e.g., Geol. Mag., 1907, p. 70. 
t Cf. Phillips, Geology of Yorkshire, Vol. TI., 1835, p. 14. Sharpe, F., 
Proc. Geol. Soc., Vol. III., 1842, p. 605. Godwin, Austen, Quart. Journ. 
Geol. Soc., Vol. XIT., 1856, p. 53. Mem. Geol. Surv. Explanation Quarter 
Sheet, 98° S.E. Cummin, Rev. I. G., The Isle of Man, its History, &c., 
1848, p. 89. Article on Geology in History and Topography of Cumberland 
and Westmorland, by W. Whellan, Pontefract, 1860, p. 28. Ramsay, Sir 
A., Quart. Journ. Geol. Soc, Vol. XI., i 855, p. 187. The Reader, Aug. 12th, 
1865. Hughes, T. MeKenny, Notes on the Geology of Parts of Yorkshire 
and Westmorland. Geol. Polyt. Soc. Yorks, Halifax, July, 1867. Mem. 
Geol. Surv. Explanation, 98° S.E., 1872, p. 15. Recurrence of Ice Ages, 
Proc. Camb. Phil. Soc, 4 parts. Vol. VIII., 1893, pp. 98, 219, 224, Vol. IX., 
1896, p. 214. 
