MancJicster Memoirs, Vol. liii. (1909), No. 10. 3 



II. Description of the Diatomaceous Deposit. 



Associated with the bogs and alhivial flats along the 

 valley of the lower Bann— the division between Co. 

 Antrim and Co. Derr}- — is an extensive deposit of 

 diatomaceous earth, known locally as "Bann Clay." It 

 extends all along both banks of the river from Toome 

 almost to Coleraine. At Toome the deposit, so far as 

 can be judged from superficial indications, extends at 

 least a mile west of the Bann, forming what are known 

 as the Creagh meadows. It is perfectly flat and only a 

 few feet above the level of the river. It is here some 

 3 feet in thickness, and rests on about I foot of 

 peaty material overlying sand. The deposit appears to 

 be finest and lightest at the bottom, the upper portion 

 being coarser and full of impurities, and also much 

 stained in places with iron. Nearer Toome, on the 

 Antrim side of the river, it is about 4 feet 6 inches in 

 thickness, and of much the same composition. At both 

 these places it is at the surface. {Plate I.) 



Good sections are visible along both banks of the 

 river to Lough Beg. These, however, can only be 

 examined from about April to September when the 

 Bann level is below the bottom of the beds. At other 

 times the water is sometimes almost level with the top of 

 the banks. 



Below the peat to the west of Church Island, on 

 Lough Beg, the same deposit is met with, and at the 

 north end of the Lough, near the Ferry, I observed it 

 under 8 to 10 feet of peat in April, 1908, in a section 

 about a hundred yards from the river. Here, however, 

 the bed was only 18 inches thick. The overlying peat 

 was full of the roots — corkers — of large trees. Owing to 

 the saturated condition of the ground I was unable to 



