The Irish Post-Glacial Estuarhie Deposits. 139 



they have apparently been overlooked (for there is little 

 reason to suppose they are absent), and the object of the 

 present communication is to briefly describe this estuarine 

 series, and bring it under the notice of Irish geologists, in the 

 hope that information as to the occurrence of similar deposits 

 on other portions of our coasts may be forthcoming. 



I shall take a typical section at Belfast (Alexandra Dock) 

 as an illustration. Here the strata passed through in exca- 

 vating for the graving dock were as follow: — 



ft. in. 

 Surface clays, . , . . . . . . 6 6 



In almost every section of the estuarine beds, the Boulder 

 clay forms the base, and it is much older than the oldest 

 member of the series with which I am dealing. While the 

 Boulder clay is characterized by northern and arctic forms 

 of molluscs, the estuarine fauna presents a rather more 

 southern aspect than that now^ existing in the same area. 

 The red sand which overlies the Boulder clay at Belfast is the 

 representative of a long period of time, during which the 

 climate returned to something approaching its present con- 

 dition, and it probably corresponds in age with the eskers of 

 the inland counties, and with brick-earths and gravel deposits 

 in many parts of the countr}^ ; a few starved foraminifera 

 attest its marine origin. Ikying above this red sand, between 

 two layers of gre}^ marine sand, we meet with a bed of peat. 

 This peat forms a well-marked zone, occurring at points all 

 round the Irish coast, and it may be taken as the base of the 

 estuarine series. In the north-east it occurs at a large num- 

 ber of localities, varying in level from above high water mark 

 to some thirty-five feet below that level, and in thickness from 

 a few inches to four feet. It contains an abundant flora of 

 marsh plants, and leaves, fruit, and branches of Scotch fir, 

 hazel, willow, alder, etc. ; the first two largely predominating. 

 The tree-stumps are usually still in the natural upright 

 position. At Belfast the peat has yielded remains of the Red 

 Deer, Irish Klk, and Wild Boar. The occurrence of a Megace^vs 

 skull in this bed is particularly interesting, as placing the 

 submerged peat on a horizon corresponding with the marl 

 deposits which underlie our great peat-bogs, rather than with 

 the peat-bogs themselves, in which Megaceros remains seldom, 

 if ever, occur. 



