498 Prof. Cole & T. Hallissy—The Wexford Gravels. 



V. — The Wexfokd Geatels and their beaeing on Inteeglacial 



Geology. 



By Grenville a. J. Cole, M.E.I.A., P.G.S., and T. Hallissy, M.E.I.A., 

 Geological Survey of Ireland. 



I. Inteoduction, 

 rpHE shell-bearing gravels of the county of Wexford have become 

 JL so well known on account of their fossil contents that the 

 boulder-clays associated with them have received scanty recognition. 

 Very diverse statements have been made in regard to the position of 

 the gravels in the succession of superficial deposits, and they have 

 frequently been confused with the 'marl' which was extolled by 

 early writers upon agriculture. Nearly all the references to the 

 manurial value of such materials in Co. Wexford refer to this marl, 

 that is, to a shelly and calcareous boulder-clay. The gravels, however, 

 have been commonly styled ' manure gravels ' by geologists, and 

 E,. J. Griffith,' as far back as 1836, distinctly states that the shells 

 are sometimes so very numerous "that the gravel is raised for 

 manure ". 



Numerous 'marl pits', now sometimes overgrown, remain on the 

 farm lands of the countj^, and their use is well remembered by the 

 people. Their original development is quaintly referred to in Boate's 

 Natural History of Ireland ^ — 



" The same," i.e. marl, " also is still very usual in sundry parts of England, 

 being of an incomparable goodness : the wliicli caused the English, who, out 

 of some of those places where Marl was used, were come to live in Ireland, to 

 make diligent search for it, and that with good success at last ; it having been 

 found out by them within these few years, in several places ; first in the 

 King's-county, not far from the Shannon, where being of a grey colour, it is 

 digged out of the bogs ; and in the county of Wexford, where the use of it was 

 grown very common before this rebellion, especially in the parts lying near the 

 sea ; where it stood them in very good stead, the land of itself being nothing 

 fruitful. For although the ground (for the most part) is a good black earth, 

 yet the same being but one foot deep, and having underneath a crust of stiff 

 yellow clay of half a foot, is thereby greatly impaired in its own goodness. In 

 this depth of a foot and a half next under the clay, lieth the Marl, the which 

 reacheth so far downwards, that yet nowhere they are come to the bottom of 

 it. It is of a blew colour, and very fat (which as in other ground, so in this, is 

 chiefly percieved when it is wet) but brittle and dusty when it is dry." 



E,. Eraser, in his Statistical Survey of the County of Wexford,'^ 

 refers only to the ' marie ' as being laid upon the land, and his 

 description makes it evident that this marl was a boulder-clay 

 containing marine shells. 



E,. J. Griffl.th (Sir R. Griffith) came across the deposit when 

 engaged in his remarkable geological survey of all Ireland.* He 

 notes an "extensive marl deposit in Wexford, some of the shells of 

 which appeared to correspond with those of the crag". A year later 

 he amplified this observation in a presidential address to the Geological 



■^ Journ. Geol. Soc. Dublin, vol. i, p. 151. 

 " Edition by Thomas Molineux, Dublin, 1755, p. 57. 

 ^ Dublin, 1807, pp. 53-5, 76-8, 81, 85. 



■* "On the Geological Map of Ireland": Eep. Brit. Assoc. Dublin, 1835, 

 Transactions, p. 58. 



