751 
of Edinhurgh, Session 1883—84. 
that terrace, and then reach the short slope or bank that overlooks 
the 25 feet beach and the modern alluvia (see fig. 3). And just as 
the deposits of the 25 feet beach pass up the valley of the Esk into 
well-marked haughs of river alluvia, which gradually ascend with 
the slope of the valley ; so, when we follow the deposits of the 
older terrace inland we find them in like manner rising to a gradu- 
ally higher level, and behaving in every respect like ordinary river 
alluvia. There cannot, therefore, be any doubt, I believe, that the 
sand and gravel which contain the drifted trees are of fluviatile origin 
— accumulations formed by the Esk, at a time when that river flowed 
at a higher level and in considerably greater volume than at present. 
Since the upper or 45-50 feet terrace was formed the River 
Esk has cut its way down through that terrace and the boulder- 
clay and carboniferous strata to a depth of some 30 feet ; and the 
greater size of the Esk when flowing at the 45-50 feet level is 
indicated not only by the character and bulk of the deposits then 
laid down but by the much wider area over which these extend. I 
think it is also suggested by the great size of the drifted trees, which 
could hardly have been floated seawards by such a stream as the 
modern river. 
It is of some interest now to inquire what relation this ancient 
alluvial terrace bears to the raised beaches which occur at so many 
different places on both sides of the Firth of Forth. From what I 
have seen of those old sea-beaches I have little doubt that the tree- 
bearing beds referred to in this communication are on approximately 
the same geological horizon as the well-known 45-50 feet beach ; 
that, in short, the sand and gravel in which the great trees occur 
were deposited at or near the mouth of the Esk, when the 
sea-level stood some 45 feet higher than it now does. This 
appears to be shown by the fact that the upper limit of the 
terrace at Musselburgh preserves the same level when followed from 
west to east across the valley of the Esk, and hardly begins to show 
any rise when traced up that valley until we reach Inveresk. In 
short, the deposits at Musselburgh seem to me to resemble the delta 
accumulations of a very considerable river, and it is just possible 
that some of the current-bedding seen in the sand-pit at Olive Bank 
may be the result of tidal action. But the body of fresh water 
flowing seaward would be sufficiently great to prevent the incursion 
