On the so-called Raised Sea- Beach Bed at Leith. 425 



portion of sand, and several horizontal layers of sand and 

 gravel distinctly stratified, one of which, at 6 feet below the 

 surface of the clay, was 16 inches thick, and could be traced 

 for 20 feet. 



The Akumite group in the ascending order of the super- 

 ficial strata consists of three distinct kinds of deposits — silt, 

 sand, and gravel. Sections occur in this neighbourhood to 

 prove that, subsequent to the deposition of the Taragmite 

 series, and previous to the commencement of the Akumite 

 group, extensive denudation had taken place, by which the 

 newer or upper portion of the Taragmite beds had been re- 

 moved. In all the sections examined in this neighbourhood, 

 the silt appears as the basement bed of the Akumite series, 

 and, where present, is seen to rest immediately on the boulder- 

 clay. There is evidence to show that in all probability the 

 Akumite group may be regarded as a lacustrine formation, 

 into which marine remains have occasionally been thrown by 

 irruptions of the sea. Like the Taragmite formation, in pass- 

 ing upwards it graduates into sand and gravel ; and where 

 sand occurs without the boulder-clay or silt being exposed, its 

 true relation cannot be satisfactorily determined. There are 

 grounds for supposing that deposits of sand belonging to the 

 boulder-clay and silt periods have been frequently confounded 

 with a bed of marine sand of a different origin, to which the 

 name of raised sea-beach bed has been given. This bed be- 

 longs to the third group in the ascending scale, or Phanerite 

 series, of the superficial accumulations ; and although, as its 

 name implies, it presents characters very distinct and easily 

 observed, it has nevertheless formed the subject of much 

 geological controversy. 



At the concluding meeting of the Royal Physical Society 

 for 1859, I gave a brief description of that portion of the so- 

 called raised sea-beach bed which extends between the old 

 sandstone quarry at Granton and the Magdalen Burn, near 

 Fisherrow. I then stated that the lateral extent of this so- 

 called raised sea-beach bed, and its relation to other accumula- 

 tions of a similar lithological structure, but destitute of any 

 trace of marine remains, had not yet been satisfactorily deter- 

 mined. The importance of this investigation will be readily 



