8 Proceedings of the Royal Irhh Academy. 



The eruptions recorded in the annals may be divided into two 

 groups (-R-hich might be subdivided into minor groups), between the 

 occurrence of which a long lapse of six centuries and a half is related 

 to have taken place. However improbable may be the pre-Christian 

 chronology here, as respects the events attributed to particular years, 

 it seems reasonable to suppose that a succession of epochs might have 

 been noted accurately. I am inclined to credit this, in the present 

 case, for the following reasons : following on a map the chronicled 

 eruptions of lakes, I united the latter, so far as identified, by straight 

 lines. To my surprise I found these lines arranging themselves north and 

 south, in a direction parallel to the lines of longitude. Thus it was 

 with respect to Lough Conn and Lough Mask in the west, to Loch 

 Laighline in east ileath; and Loch Eochtra, orlCucnama, in!Monaghan; 

 to Derryvaragh and Ennel, in ^"estmeath ; and to a few others. About 

 foui" lines, running north and south, each including two or more lakes 

 in their coui'se, appeared on the map. 



From the end of the Xemedian period, during all the Firbolgic and 

 De Dananian days,--' until the llilesian epoch had begun, no outburst 

 of lake or river is recorded. A long interval of six centuries and a 

 half, therefore divides the first great group of lake eruptions from the 

 second group, in which the eruption of both lakes and rivers is 

 mentioned. ISow, it struck me as curious that the lines connecting 

 the principal lakes enumerated lay in a different direction. Instead 

 of running north and south they run obliquely from south-west to 

 north-east. Thus, a line drawn from Clare to Belfast will fall more 

 or less near eight lakes, whose eruptions are recorded, Anno ]y!undi, 

 3503 — they are Lochs Graney (Co. Clare) ; Cimbe (now Hackett, Co. 

 Galway) ; Loch Baah (Co. Eoscommon) ; Een and Garadice (Co. 

 Leitrim) ; and Loch Laegh, now Belfast Lough. At this period, cer- 

 tain, rivers break forth; and of these the Brosnac, the Socs (now Suck), 

 and the Inny, flow towards this line from west and east, whilst others 

 in the north, such as the Una in Tyrone, and the Callan in Armagh, 

 and (perhaps), the Fregrabail (now the Eavelwater, in Antrim), 

 appear related to it. 



The next oblique line runs almost parallel to this on the north- 

 west; it covers in its course the recorded eruptions of Loch Foyle, 

 Loch Erne, and an irruption of the sea, forming what is now Drum- 

 cliffe Bay. Towards this line tend the three Finns, whose eruption is 

 there recorded, and perhaps, some other streams named by the anna- 

 lists, but not identified by recent writers. Here again, we find some 

 isolated cases ; and rivers are mentioned as having bm'st forth in the 

 south-west. 



Bearing in mind the evidences of change of levels which some of 

 our beaches present, and the proofs of depression and elevation in the 



* Lough Corvib [Loch Oirbseii] was formed in the D.ananian period, according to 

 the Book of Leinster. 



