26 A. MacEicen Teach — Glacial Distribution of 



inch bore, discharging 700 gallons u minute from a ten foot stratum, 

 the water would have a velocity of 5^ feet a second at the bore itself, 

 at a distance of one mile it would only be moving through the stratum 

 at the rate of about -^lo inch per second, or 18 inches an. hour. 



Further consideration of the conditions governing artesian flows 

 must, however, be reserved for a future occasion. In the meantime 

 I have to tender my thanlcs to the members of ray staff in the oasis for 

 much valuable assistance in the keeping of records of all bores put 

 down during the past three years. 



VII. — BotacER Distribution from Lennoxtoavn, Scotland. 



By A. MacEwex Peach. 



A LTHOUGH the general path of the ice-sheet of the central valley 



j\_ of Scotland has been traced, no advantage has, up till now, 



been taken of the glacial distribution of boulders from a peculiar 



intrusive rock, which occurs in the Campsie Fells near Lennoxtown. 



The rock of which the intrusion is composed was first described 

 by Allport in the Quarterh^ Journal, Geological Society of Loudon, 1 874, 

 vol. XXX, p. 559, as a porphyritic augite-olivine dolerite, and has later 

 been determined by Mr. E. B. Bailey to be an essexite. He has also 

 mapped the boundaries of the intrusion during the revision of that 

 district by the Geological Survey. 



From the distinctive characters of this rock, and tlie distribution 

 of boulders from it in the neighbourhood of Milton and Kilsyth, 

 Mr. Bailey was struck with its suitability as a means of determining 

 the direction of ice-flow during the Glacial period, and it was at his 

 suggestion that I undertook the task of extending his observations. 



Mr. Bailey has shown that the Lennoxtown essexite is intruded 

 into the lower portion of the interbedded volcanic rocks immediately 

 overlying the Ballagan Beds of the Calciferous Sandstone Series, 

 which forms the base of the Scottish Carboniferous formation. It 

 borders the north side of the Crow Road leading from Lennoxtown 

 to Fintiy, about a mile north-west of the former, Avhere the road 

 crosses the great east and west fault which lets down the Hosies and 

 Hurlet Limestones to the south against the volcanic series to the 

 north. The outcrop of the intrusion is small, being only about 

 700 yards long and 100 yards wide; it has a roughly east and west 

 trend, and lies between the 500 and 600 foot contour-lines. 



In composition and structure the Lennoxtown essexite greatly 

 resembles the well-known rocks of Braudberget in Kristiania and 

 Crawford John in Lanarkshire. The variety which has been of most 

 service in the present enquiry carries markedly porphyritic, idiomoi-phic, 

 purple augites in a ground-mass much like that of a fine-grained 

 gabbro, and thus presents a very distinct appearance, as, in the 

 weathering of the rock, the augites remain prominent and more or 

 less unaltered. 



The only known rocks of similar external appearance, which are 

 likely to be distributed as erratics in the district under consideration, 

 are certain augite diorites of the West Highlands. Risk of confusion 

 has been avoided by neglecting the very few boulders in regard to 

 which there existed anv room for uncertaintv. 



