REPORT OF MEETINGS FOR 1905 257 



US of his invaluable aid in reproducing the explanation 

 then offered, as well as of a specially written paper 

 indicative of his views regarding the geological formation of 

 the neighbourhood of Edinburgh ; but in order to supply 

 an index to his individual judgment in the matter, and to 

 offer a tribute to his willing services towards the advancement 

 of scientific research among the Berwickshire Naturalists, 

 there follow abbreviated notes, from the Proceedings of the 

 Geologists' Association, of an Outline of the Geological History 

 of Arthur's Seat, which was read by him in 1897.* The 

 earlier chapters of this geological history supply a record 

 of an old land surface, probably formed mainly of rocks 

 belonging to the Caledonian Old Red, but partly also 

 shaped out of the ends of highly contorted Silurian and^ 

 other rocks, of still greater age. Ample reason exists for 

 believing that such a surface was marked by much irregularity 

 of form, though whether any of the eminences now in existence 

 were at that period conspicuous is matter of uncertainty. The 

 Upper Old Red Sandstone, which is distributed generally 

 throughout this area, affords evidence of an age when arid 

 conditions prevailed, for whatever rain may have fallen was 

 too intermittent in its occurrence to allow of the growth of 

 vegetation. Under such conditions a series of deposits was 

 formed, which partook of the nature of accumulations of 

 wind-blown sands, or of torrential drifts, which filled up the 

 old water-courses ; and therefore the distribution of the Upper 

 Old Red Sandstone is very irregular, spaces abounding where 

 no indications of such deposits exist at present. Towards the 

 close of this period subsidences of a local nature occurred, and 

 continued for a space, thereby introducing new meteorological 

 conditions. Rain fell with greater regularity, the measure of 

 aqueous vapour in the atmosphere considerably modified the 

 diurnal range of temperature, and rock-weathering of the 

 normal type prevailed. With the return of humid conditions 

 vegetation flourished, and animal life began to abound. As 

 yet the sea had not gained a permanent entry ; but the area 

 probably formed part of a lagoon, or a series of lagoons, 

 exposed to the alternate processes of flooding and desiccation, 



* Vol. XV., Pt. 4, August 1897. 



