4 Jackson, Deposit of the Loiver Bann Valley. 



ascertain the exact nature of the beds ininiediatcly below 

 the diatom deposit. 



Between Lough Beg and Portglenone it is from 

 4 to 6 feet in thickness, resting in some places on a dark 

 gray stiff clay, and in others on a layer of peaty soil. 

 The banks of the river near Culbane and Portglenone are 

 about 5 feet high and consist of a small covering of 

 surface soil, then the diatom deposit, and below that a 

 clayey peat. At some little distance from the river the 

 deposit passes under peat of the ordinary kind. 



Opposite Culbane, on the Antrim side, the same 

 deposit is 6 feet thick under 3 to 6 inches of soil, and 

 rests on what appears to be a blue marl. 



North of Portglenone the deposit nearly disappears, 

 being only i foot deep at Annaghcraw. Near Portna it 

 lies 2 feet deep over peat, and again makes its appearance 

 along the narrow flat stretch north of Kilrea — 15 miles 

 from Toome — and ultimately dies out south of Coleraine. 



This vast deposit is of great commercial value, and 

 several firms are working it at Toome and Lough Beg. 

 At Toome it has been worked for several years by 

 Messrs. J. & F. Grant, to whom I am indebted for much 

 information. The following chemical analysis was made 

 by Messrs. R. R. Tatlock & Thomson, of Glasgow, on a 

 sample taken from their works : — 



Raw. C.ilcined. 



Silica 74"90 per cent 8 7 '66 per cent. 



Alumina 6'68 ,, 782 ,, 



Iron O.xide 1*90 ,, 2'22 ,, 



Lime I'oi ,, i"i8 „ 



Magnesia '72 ,, -84 „ 



Alkalies 24 „ 28 „ 



Organic matter and 



combined water .. 7-20 ,, — 



Moisture 7'35 ,, — 



lOO'OO ioo"oo 



