The Scottish Naturalist. 



343 



containing trunks of trees, seeds of the marsh trefoil, or buck-bean, 

 and other marsh plants, besides horns of the red deer and elytrse 

 of beetles ; and in one section, at the Gas Work, the seed of a 

 cereal like our barley was found. This peat deposit was exposed 

 when the Dock was made in 1842 ; again in 1866 at the Gas 

 Work, where an excavation was made for a new tank ; and again 

 at the cutting at Redfield for the connection of the North British 

 with the Bervie Railway ; while much of it was brought up and 

 carried out to sea by the dredgers, while deepening the harbour 

 some years ago. 



After this bog period the land must again have been depressed ; 

 for we find overlying it a thick bed of estuary silt, containing 

 characteristic shells, such as Scrobicularia, Tellina, Littorina^, 

 Rissoae, cockles, &c; and at the Redfieid section the skull of an 

 ox (Bos longifrons) was found. Again a further depression took 

 place, for over the silt at Redfield we have a bed of fine laminated 

 sand, four feet in thickness, and over it five feet of Carse clay 

 destitute of fossils, and indicative of a further wash-out of the 

 glacial debris of the Glen of Clova and its tributaries. 



The following explanation of the changes evinced by these 

 accumulations is quoted from Professor Geikie's " Pre-historic 

 Europe " (p. 404) : 



" 1 st. Long after the retreat of the glacial sea, the land ex- 

 tended considerably farther out to sea than it does now, and the 

 climatic conditions were certainly not less genial than they are at 

 present — an arboreal vegetation clothing the country. 



" 2nd. A period of submergence ensued, when the sea advanced 

 inland beyond its present limits, and reached to a height of not 

 less than 20 feet, and probably as much as 45 feet, above its 

 present level. Scrobicularia piperata and other shells then 

 flourished in abundance in what are now the lower reaches of the 

 river Esk. 



" 3rd. The Esk by-and-bye carried down immense quantities of 

 fine grey and yellow silt, with which it choked up the estuary — 

 the upper reaches of which would be greatly freshened by the 

 abundant influx of river-water. It is for these reasons that the 

 carse clays in the upper part of the old estuary are, as Dr. 

 Howden has shown, unfossiliferous. The phenomena indicate, as 

 it seems to me, conditions quite analogous to those presented by 

 the carse deposits of the Tay. Local glaciers then occupied the 



