548 SECTIONAL TRANSACTIONS.— C. 



wards along the northern slope of the Kilpatrick Hills to Bonhill in the Vale of Leven, 

 and thence north-westwards by Tullichewan Castle, Auchindennan Muir, and 

 Bannachra Muir to Inverlauren in Glen Fruin, at which point it turns north-eastwards, 

 and ascends the slope of Shantron Hill. A corresponding morainic feature has been 

 noted in Glen Finlas, and on the west side of the loch at various points between 

 Rowardennan and Balmaha. The Glen Fruin section of the moraine has long 

 been known, and has been described bv Bell (1893), Renwick (1895), and Gregory 

 (1907). 



The complete absence of morainic deposits on the boulder clay outside the moraine 

 and their abundance within it, the marked lobing of the moraine up valley outwards 

 from Loch Lomond, and the manner in which it ascends to higher levels on hill slopes 

 athwart the course of the ice stream, point to this glaciation being due to a distinct 

 re-advance of the ice, and not merely a phase in the retreat of a larger ice-sheet. 



Probably the main outlet of the melt-waters of the glacier was by the Vale of 

 Leven gap. ' Here an extensive outwash fan of gravel has been deposited. Below the 

 50-foot level this was subsequently re-sorted, in a large measure by the sea that formed 

 the Early Neolithic Beach. Above the height mentioned the fan sloped gently 

 upwards and merges with hummocky gravel deposits within the moraine. 



Interesting features within the terminal moraine are : 



(1) A belt of gravel spreads and morainic mounds, the latter sometimes con- 

 centric with the outer moraine. 



(2) A system of drumlins radially disposed with respect to the upper reaches of 

 Loch Lomond. 



(3) Marine shells, indicative of cold-weather conditions, widely dispersed in the 

 boulder clay. This fact was first noted by Jack (1875) who, like the writer, attributed 

 their presence to land ice dredging out Loch Lomond, an arm of the sea. These shells 

 have been noted in new localities close up to the moraine ; but never in the boulder 

 clay outside, which is otherwise similar to that within. 



(4) South and east of Drymen, and resting on this shelly drift, a wide expanse of 

 sand, gravel and laminated clays also with marine shells. -Jack regarded these deposits 

 as marine, and this view has' lately been upheld by Gregory (1928). Geilde (1894) 

 favoured a lacustrine origin for them, pointing out that the shells could be derived 

 from the underlying shelly drift. Bailey (1925) strengthened this interpretation by 

 drawing attention to an overflow channel near Balfron by wluch the waters of this 

 postulated Drymen lake, held up by ice to the west and south, escaped eastwards. 

 The writer agrees with the freshwater hypothesis, and in support of this advances the 

 further point that the shells in the gravels are so widespread that it is unlikely that 

 they are wholly derived from the drift, and it seems much more probable that 

 they were dredged by the ice from the old sea-floor of Loch Lomond, carried forward 

 as englacial material, and ultimately discharged by the melt-water into the 

 Drymen lake. 



At Inchlonaig, six miles from the foot of the loch, Craig (1900) records contorted 

 shelly marine sediment at 100 feet overlain by boulder clay, and postulates a 

 recrudescence of glacial conditions to account for this. The additional facts noted by 

 the writer point to this re-advance of the ice being of much greater magnitude than was 

 previously supposed. At Dumbarton on the Clj'de estuary the 100-foot beach deposits 

 are developed, and continuing up the Vale of Leven comparable sediments are 

 traceable at intervals to within a mile of the moraine. No corresponding platform has 

 been detected within this limit, and morainic mounds descend to a level of about 

 60 feet. From this latter observation we may conclude that the final retreat of the 

 ice was not earlier than the emergence of the land that took place after the deposition 

 of the 100-foot beach. 



Mr. D. Tait. — On the Occurrence of Peat or Lignite under Boulder Clay, 

 near Glasgow. 



The deposit described was met with during the construction of the western part 

 of the new Glasgow-Edinburgh road at a point about one mile east of Alexandra Park 

 and a little south of Gartcraig House (one-inch Geological Map, Sheet 31 ; six-inch 

 sheet Lanark vi S.E.). Here a cutting with a length of about 200 yards and a 

 maximum depth at its centre of 12 to 15 feet was made through a low rounded mound. 

 When newly exposed the section was as follows : — 



