34 H. C. Collyer on 
through a jagged rocky gorge, which makes a magnificent sight from 
the railway above Spean Bridge. How could that small stream 
have exerted such extraordinary power at this point to break up 
and destroy its rocky bed? Probably this gorge was cut by 
the escape of the waters of Loch Spean under the Ben Nevis 
glacial snow-drift. The river from that point still skirts the 
position that that snow-drift then occupied, instead of running 
straight across to Fort William. 
This snow-drift ice-block theory seems to explain all the details 
of the parallel ‘‘roads.’”’ The upper ‘‘road’’ comes down to the 
margin of the ice, in the first stage drawn, and no further. The 
middle ‘‘road"’ reaches the retiring edge of the block, as drawn 
in the second position. And both these ‘‘roads” wind into the 
upper part of Glen Collarig, and stop at the place where the ice 
stood in that glen then. The lowest ‘‘road’’ occurs everywhere 
above the last boundary of the obstructing dam. It does not 
wind into the upper end of Glen Collarig from Glen Roy, for 
that is at too high a level, but it runs up the lower half of Glen 
Collarig from Glen Spean. Also this ‘‘road’’ is marked less 
clearly in the lower part of Glen Spean, into which the lake had 
not long advanced; while in the upper part of Glen Spean, 
where the lake must have existed much longer (from the very 
beginning of the upper ‘‘road”’), there the water-level is repre- 
sented by very broad stony terraces, and by the big delta which 
the River Gulbin formed when Lake Spean flowed eastwards. - 
Thus, merely assuming that the Glacial Epoch only very slowly 
passed away, this simple and natural theory completely and 
accurately accounts for the exact position and extent of all the 
parallel ‘‘roads,’’ points out evidence of the successive débacles 
by which the lakes were lowered, and explains it all as the 
natural result of the physical conditions at present existing. 
7.—Japr on NEPHRITE. 
By H. C. Coutyer. 
(Read December 15th, 1903.) 
Tue subject of the paper this evening is one which was for a 
long time involved in a considerable amount of mystery, which 
has even now not been entirely cleared up. Jade and its kindred 
minerals have been found in use in several parts of the world 
where the stone itself is not known to exist; for instance, at the 
