Memoir of the Rev. Thomas Broiun. 345 



contradiction they seemed to give to the prevailing notices 

 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 neighbourhood, he would not have tried 

 80 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 determination 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 co'lection of the old gravels of which 

 the river floods formed the terraces. Reference 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 attention of geologists. If we are ever to have 

 a trustworthy scheme of the order of superposition of 

 Quaternary deposits, and a biotic scheme co-ordinate with 

 that of superposition, they are likely to result from such 

 careful observation and orderly records of relation and 

 sequence as distinguished Dr Brown's labours in this depart- 

 ment. 



