301 
of Edinburgh, Session 1876-77. 
the knolls referred to were composed entirely of beds of sand and 
fine gravel, — manifestly deposited by water, and not brought by 
a glacier. 
The supposed Moraines, between Rough Burn and Fersit, con- 
sist of enormous embankments of gravel, apparently sub-marine, 
and formed when the sea stood some thousands of feet above its 
present level. The boulders strewed over this district, and heaped 
on these embankments, had probably been brought by floating ice, 
in a current from the westward, flowing up the valley of Spean 
towards Strathspey. 
7. In regard to Dr Tyndall’s lecture, Mr Milne Home pointed 
out, that when impugning the soundness of the detrital barrier 
theory, Dr Tyndall had given a representation of that theory only 
from Sir Thomas D. Lauder’s Memoirs, written fifty-nine years 
ago, and not from the more recently published Memoirs, which 
stated facts and arguments not to be found in Sir Thomas Lauder’s 
paper. Moreover, Dr Tyndall had unfortunately misapprehended 
Sir Thomas Lauder’s views regarding the formation of the barriers, 
ascribing to him views on this subject disparaging to the detrital 
theory, which neither Sir Thomas nor any other author entertained. 
The only specific objection to the detrital theory suggested by 
Dr Tyndall, was the alleged absence of any traces of barriers. 
Mr Milne Home stated that he thought there were traces; and 
that, even if there were none, the want of them would be no valid 
objection to the theory. 
With regard to the grounds on which Dr Tyndall maintained 
the glacier theory, Mr Milne Home stated that Dr Tyndall ought 
to have shown, how there could be such a difference in the climatic 
condition of the two sides of Spean Yalley, that while the glens on 
the south side were filled with ice, the glens on the north side were 
filled with water; — this, however, Dr Tyndall had failed to do. 
Mr Milne Home farther stated that though it was undoubtedly 
true that some traces of glacier action were visible in various parts 
of Lochaber, these, as it seemed to him, belonged to a period in the 
world’s history long antecedent to the lakes of Glen Roy and Glen 
Spean. When these lakes existed, the water of the Spean lake 
penetrated into the two glens (Corry N’Eoin and Treig), supposed 
to have been occupied by glaciers. It was therefore a physical 
