398 G. S. Kinahan — Irish Silurian Land Plants. 



are simply the great secular suramers and winters of our globe, 

 depending as truly as the annual ones do upon planetary motions, 

 and like them also fulfilling some important ends in the economy of 

 Nature. 



III. — Land Plants in the Irish Siltjuians. 

 By G. H. Kinahan, M.E.I.A. 



THE land-plants lately discovered both in ' the American and 

 Continental Silurians seem to be attracting attention, while 

 those found in Ireland nearly a quarter of a century ago appear to be 

 quite forgotten. This is probably due to the unsatisfactory condition 

 in which the classification of the Irish Silurians are left at the 

 present time ; perhaps therefore it is allowable for me to give a 

 short description of these rocks. 



There are considerable areas in different parts of Ireland in which 

 the rocks are apparently of about similar age ; the larger of these 

 being : 1st, a tract in the Dingle Promontory, county Kerry {Dingle 

 heels) ; 2nd, a very extensive area in South-west Cork ( Glengariff 

 grits) ; 3rd, a tract South-west of Clew Bay, county Mayo {Louisburgh 

 group) ; 4th, an area east and north-east of Clew Bay {Croaghmoyle 

 conglomerates) ; 5th, a long narrow tract in thfe Curlew Mountains, 

 counties of Sligo and Eoscommon (Lough Gara beds) ; 6th, an ex- 

 tensive area in tlie counties of Fermanagh and Tyrone {Fintona and 

 Slievemore group) ; but besides these there are some small patches. 

 In these rocks good fossils are not recorded ; excepting the Glengariff 

 grits, which contain tracks probably Crustacean at the Light House, 

 Valencia Island ; fucoids (?), on the shore of Valencia Eiver ; plants 

 (?) on the south side of Beginish and on the sea-shore near Puffin 

 Island ; on the west side of Coomasaharn Lake, south-east of Kells, 

 plant-stems, some of them an inch and a half in diameter, and 

 irregularly ribbed in a longitudinal direction ; and in the Glengariff 

 grits, south and south-west of Killarney, imperfect plants were 

 observed in many places, the most perfect occurring in the Owen- 

 reagh valley north of Windy Gap. 



In the later editions of Griffith's map the Dingle, Glengarifi", and 

 Louisburgh rocks were classed as Silurians, while the others pro- 

 visionally were placed as Old Eed Sandstone, because, as stated by 

 that eminent geologist, he never had time to properly examine them. 

 During the progress of H,M. Geological Survey it was found that the 

 Glengarifi" grits were conformable with the overlying Carboniferous 

 rocks in the county of Cork ; while in the year 1854, low doion near 

 the bottom of the Glengariff grits, Du Noyer found plants, and in the 

 following year I also found them ; these plants were supposed by 

 the late Mr. J. W. Salter to be of Carboniferous types. In 1856, 

 Du Noyer, in the Dingle Promontory, found that similar rocks to 

 the Glengariff grits (as had been previously known to Griffith) lay 

 conformably on rocks containing typical Silurian fossils, while they 

 were overlaid unconformably by about 5000 feet in thickness of Old 

 Eed Sandstone (Lower Carboniferous Sandstone). In the autumn 

 of the same year these rocks were visited by Griffith, Murchison, • 



