Ohitiiary Notices. 
XXXlll 
to be, “ How was this valley formed ? ” Lyell thought that “ river 
erosion” will account for most of the phenomena, but added, “I 
should infer considerable oscillations in the level of the land in that 
part of France.” Murchison took up the same position, but claimed 
for the phenomena the action of much stronger and intenser forces 
than Lyell associated with them. In a word, the interest taken in 
the alleged facts and their discussion was because of the violent 
contradiction they seemed to give to the prevailing notions as to the 
time man had been on the earth. That Mr Brown had felt the 
influence of all this is clear from the summing-up of the results of 
his observations in the valleys of the Earn, the Teith, and the 
Spey. As I was myself much interested in the questions raised, I 
visited the valley of the Somme just when the discussions were at 
white heat ; and when this paper was read, I had an impression that, 
had Mr Brown spent a few weeks in Abbeville and its neighbour- 
hood, he would not have tried so earnestly to make good an alleged 
analogy between the formation of our Scottish river valleys and 
those of England and France. There are proofs of oscillations 
within the area over which the Somme gravels are spread, to which 
there is nothing analogous in the gravels of the Earn and the Teith. 
But all this by the way ; and apart from all this, Mr Brown’s paper 
bears in every page the marks of thoroughly scientific work — marks 
which come out in the careful examination of the valleys, the deter- 
mination of the relations of the terraces, their levels above the river- 
beds, and their geological sequence as deposits begun at the close 
of a glacial period. Then, he argues, came the kames or escars, and 
last, the collection of the old gravels of which the river floods formed 
the terraces. Eeference is made to the old river terraces of the 
Spey in support of the Earn and Teith inferences, and, it is asked, 
how are we to explain the action of the river in throwing up 
deposits 60 or 80 feet ? The answer is, either by floods sufficient 
to raise the channels to that height, or by supposing the bed of the 
stream to have been formerly at a higher level than now. Mr 
Brown pleads in behalf of the former. 
The value of these papers on the geology of the surface cannot 
well be over-estimated. They present, in a most lucid and 
thoroughly scientific way, questions which still occupy the atten- 
tion of geologists. If we are ever to have a trustworthy scheme of 
