To promote a wider interest in the science of geology through organised lectures, field excursions and social activities.
To provide a link between the amateur, the student, the teacher and the professional geologist.
To foster interest in geological sites within the area with a view to their study and wise conservation.
To establish and maintain good relations with organisations that have common interests.

 

 

 

 
 
 

 

 

By Ian Donaldson
The low boglands to the north of Lough Neagh have been cut away in places and the material piled up to dry, like a working peat bog. Up close, however, these heaps are not black, like freshly cut turf, but white, and lumps of it are astonishingly light, as light as cork. This remarkable material is the Bann Clay. For almost 200 years it has been excavated here, for it is almost pure silica, and has many uses.

 

 

 Originally it was made into white pottery, and later used for glazes. However as silica can withstand temperatures of 1900 degrees Celsius, before it starts to melt, this infusible earth became more useful as a refractory material, both in furnace bricks, and as a safer alternative to asbestos in insulation. Its inertness is useful as a filter for water purification, in the chemical industry, and in brewing. It is used as a filler for paints, plastics and rubber. It can absorb four times its weight of water, and is also an abrasive. Indeed, finest grades have been used in toothpaste.


The clay is made entirely of the microscopic skeletons of diatoms, mostly crushed. These are unicellular aquatic plants, a subdivision of the algae. Their silica shells are symmetrical, and often round or oval. They are a major constituent of plankton, and an important source of food for aquatic animals. They are found world-wide in most surface waters, marine or fresh, and every river has its own specific species. This is useful in forensic science, to identify how, when and where a victim died.


The deposits around Lough Neagh were formed after the last ice age, for they overlie the drift, and Neolithic implements and Bronze Age artefacts have been found in close association. The lake was much larger then, and the flat lands around must have been flooded for a long time, for in places this diatominous earth, or diatomite, is up to six feet deep.