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188 Reports & Proceedings—Geological Society of Glasgow. 
in the basalt, the first being a large replacement of the basalt by 
a deposit of siliceous material, which was itself subsequently, in 
a considerable measure, removed and replaced by a deposit of calcite. 
‘II1I.—Geronoeicat Soctrry or Grascow. 
At a meeting of the Geological Society of Glasgow, held on 
January 18, 1916, Mr. Alex. Scott, M.A., B.Sc., read a paper on 
““The Physiography of Glen Lednock’’. He pointed out the place 
of Glen Lednock in the general valley system of the Highlands, and 
said that the glen now contained a number of dry river channels, 
only one of which was now in use. It was pointed out that the 
fragments, now isolated, could be pieced together with fair certainty. 
The position of each of these fragments was described, and the reasons 
for their formation and successive abandonment discussed. Most ot 
these channels are fairly shallow and open, but at the Deil’s Cauldron 
the stream has cut a deep gorge, and this has been done by pothole 
action, as very fine examples of these are to be seen in the walls. 
In this case the dip of the beds seems to have played an important 
part in determining the position of the channel, but in other cases 
the junction between hard and soft rocks seems to have been the 
controlling factor.—Professor Gregory complimented the author on 
his paper, and agreed with him that Glen Lednock was of great 
antiquity and probably pre-Glacial. He also pointed out that it was 
only by the study of these river valleys that it was possible to 
elucidate the history of Scotland during the long period between 
Tertiary and post-Glacial times, as there were no deposits of that age 
in Scotland to contain a record. The study of this and similar glens 
also threw light on the question of whether movement was constantly 
proceeding on the line of the Highland Boundary Fault. The 
existence of a sudden drop in the beds of such glens points to there 
having been a sudden uplift of the country north of the fault in 
comparatively recent times.—In reply the author stated that the 
apparent rejuvenation of these glens does point to an uplift, but it 
may be due to another cause. In Glen Turret, however, the burn 
is cutting Old Red Sandstone on both sides of the fault, and therefore 
the pronounced fall in that glen supports Professor Gregory’s 
suggestion. He agreed with Mr. Macnair that dykes do have some 
connexion with the direction of the gorges. 
‘‘On an Ancient Shore-line.”? By M. Macgregor, B.Sc., H.M. 
Geological Survey. The Helmsdale Boulder Bed, with which the paper 
deals, dated from late Jurassic time, and consisted of a tumultuous 
accumulation of blocks, the majority angular, embedded in shales, 
sandstones, and shelly limestones which were contorted at the points 
of contact. The boulders had been determined as all of Middle Old 
Red Sandstone age, with a regular ascent in the series from north to 
south. The age of the bed had been determined by means of its 
plants as Kimmeridgian, and by means of a coral as Portlandian. 
‘The author described the structure of the district and summarized 
the views on the origin of the boulder bed of various authorities who 
had examined it. These opinions were shown to be untenable from 
