of Edinburgh, Session 1880 - 81 . 287 
which brought them ; and therefore whatever inferences their 
position indicates, these inferences may be relied on as correct. 
Boulders in valleys, or at the foot of a hill, on the other hand, 
may by mere atmospheric action have lost their original positions, 
by having rolled to a lower level ; in which case, they can afford no 
true data for inference. 
They may, however, when found in valleys, have come there 
by local glaciers ; and such cases are mentioned in previous 
Beports of the Committee. But where boulders are on hill 
ridges or hill tops, at heights exceeding 2000 or 3000 feet above 
the sea (and cases of that kind have been mentioned in our 
Reports), in districts where there are no hills much exceeding that 
height, local glaciers as transporting agents are inconceivable ; and 
equally so seems to me the agency of a general ice-sheet moving 
over the country ; for such a raft would have the effect, not of 
depositing boulders on hill tops, but of sweeping everything off 
them. 
Second . — The discovery by Professor Heddle of one or more 
streams or trainees of boulders, in the Highlands, is very important 
by affording additional data towards the solution of the problem, 
what was the transporting agent ? The late Hugh Miller speaks of 
having seen boulders in a continuous line at two places in Mid- 
Lothian (“Edinburgh and its Neighbourhood,” p. 35) ; but the best 
examples, which I can specify, of boulders in continuous streams, 
occur in the United States. They have been described by 
Hitchcock, Henry Rodgers, and Dana, all well-known American 
geologists. One of these places was visited by Sir Charles Lyell, 
who, in a lecture at the Royal Institution, London, in the year 
1855, gave an interesting account of it. 
This lecture I have found in a volume of pamphlets in our 
library. It contains a diagram, which I have caused to be copied 
on a scale large enough to be seen on the walls, thinking it 
might be of service in suggesting further explorations in our own 
country. 
(The diagram was here shown and described.) 
The explanation of these Massachusetts boulder streams, implies 
the submergence of the country to the extent of about 2000 feet, 
under an arctic sea, capable of allowing ice to be formed. Now it 
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