252 LE Wi OOLNALVOT NG ROLOG Ne 
XI. UPPER TURBARIAN. 
The upper forest-bed is in its turn overlaid by peat —a succes- 
sion seen in the turbaries over a vast region. Followed from the 
interior to the coast-lands in Scotland this peat is found passing 
under the lower raised beaches. The Upper Turbarian was there- 
fore marked by a new advance of the sea. No moraines rest 
upon these later beaches, and this last epoch of submergence 
cannot therefore be directly connected with any of the glacial 
deposits of the interior. It is remarkable, however, that in the 
highest mountain-groups of Scotland we encounter not only the 
terminal -moraines of the Lower Turbarian, but another and 
later series, the presence of which implies a snow-line at 3500 
feet. In mountains which are under that elevation the lower 
series of moraines alone puts in an appearance. The inference, 
therefore, is that the higher-level moraines bear the same rela- 
tion to the peat-bogs and raised beaches of the Upper Turbarian 
as the lower-level moraines do to the corresponding accumula- 
tions of the Lower Turbarian. This stage must doubtless be 
represented in Norway by similar moraines at high levels —indeed 
these are well-known to exist, although they have hitherto.been 
looked upon as simply marking pauses in the retreat of the 
larger ice-flows of an earlier stage. In the eastern Alps no 
third ‘post-glacial stage” of moraines has been recognized, but 
that is because these mountains have not the requisite elevation. 
It is in the western Alps that traces of such a stage must be 
sought for, and I venture to predict that they will yet be recog- 
nized. 
I should like now to add a few remarks on the methods fol- 
lowed in this attempt to classify and interpret the complex 
accumulations of the glacial period. In working out the geo- 
logical structure of a district we all know how helpful it is to 
discover some well-marked datum-line——-some horizon, whose 
position is fixed, and to which constant reference can be made. 
Having been assured that interglacial epochs broke up the con- 
tinuity of the Ice Age, it was obviously important to ascertain 
