|Doonan Quarry, Doraville||Fermanagh|
|Doonan Quarry, Doraville, Co.Fermanagh, August 1997: access road.|
|Site Type: ||Quarry (working)|
|Site Status: ||ASSI|
|Grid Reference: ||X21933566|
|Rock Age: ||Tertiary, Devonian|
|Rock Type: ||Dolerite, Hornfels, Shale|
|Minerals: ||Analcime, Chabazite, Thomsonite, Zeolites, Laumontite, Pyroxene|
|Other interest: ||dyke, pipe vesicle, No Data|
Summary of site:
This quarry exposes a section through a multiple dyke (a set of dolerite-filled fractures), dating back 60 million years, when molten magma was injected from depth into open cracks in the Carboniferous rocks of the area.
The rocks in the quarry were close to ground surface because the reduced pressure allowed gas to bubble out of solution, creating first streams of bubbles and eventually open tubes, continuously venting to the surface. These appear as continuous pipes through the dolerite with white crystals of a group called zeolites encrusting their walls.