NOTES ON MARINB DEPOSITS OF THE FIRTH OF FORTH. 217 



Notes on the Marine Deposits of the Firth of Forth, 

 and their Relation to its Animal Life. 



By r. G. Pearcey, Naturalist to the Fishery Board for Scotland. 



[Read 27th August, 1901.] 



In 1898 I -was enabled to examine the deposits at present 

 forming the floor of the Firth of Forth, and especially those 

 found in the areas of the stations laid down for special observa- 

 tions by the Fishery Board for Scotland. 



The Firth of Forth may be taken as extending from Alloa to 

 the Isle of May. From Grangemouth to near Queensferry it 

 measures IJ miles in breadth, with a depth of less than 10 

 fathoms. At Queensferry it contracts to 1 mile, and the depth 

 increases over a small area near by to 40 fathoms, but diminishes 

 afterwards. From Queensferry the breadth increases again to 5 

 miles at Leith, and to 16 at Musselburgh. The firth again 

 contracts to 8 miles between Fidra and Chapel Ness, after wliich 

 it again widens to 18 miles across, where it merges with the 

 North Sea at the May Island. 



A. short tract of 10 fathoms, known as the narrow deep, lies to 

 the south of Inchkeith, and a few miles to the north-east of that 

 island the 20-fathom area begins, tending north-eastwards, and 

 spreading out off Largo towards both shores till quite close up to 

 the May Island. The Isle of ilay is connected to the mainland 

 of Fife by a submarine plateau, rising to within 20 fathoms from 

 the surface, and a few miles to the eastward of it depths of over 

 30 fathoms commence. 



The mean depth of the whole firth is 14 fathoms, the deepest 

 water found where deposits were obtained and examined, at 

 Station IX., is 35 fathoms. 



The greatest extent of shallow water ranges from Leith to 

 North Berwick along the south shore, across Aberlady Bay, on 

 the south side, and from Ejrkcaldy close along Largo Bay, off the 

 coast, to Fife Ness, on the north side. 



From Queensferry to Alloa the deposits cannot, in the true 

 sense of the term, be classed among the marine deposits, as this 



