ANNIVERSABY ADDRESS OF THE TRESIDENT. 75 



the same belts, these calcareous deposits must range across a tract 

 of not less than 420 miles. The quartzites form some of the must 

 striking mountain-groups in the centre and south-west of Scotland, 

 as well as in the north-west and west of Ireland. Whether we 

 regard its area, the variety and persistence of its different members, 

 or the scenic features which characterize it, this series of rocks is 

 undoubtedly one of the most important in I3ritish geology. 



Yet, strange to say, it has not yet received any distinctive name. 

 We speak of the younger schists, the quartzose and gneissose Hag- 

 stones, the upper gneiss, or use other more or less awkward peri- 

 phrases. Eut there is much need of some short adjectival name 

 which will do away with the vagueness of these various appellations, 

 and serve at once to distinguish this vast series of metamorphic 

 rocks. Such a name need not be a permanent addition to geological 

 terminology, but it might at least for some time be usefully adopted 

 as a convenient epithet until the true stratigraphical position of the 

 rocks is definitely ascertained. In selecting a suitable geographical 

 word, regard should be had to the extension of the rocks through 

 both Scotland and Ireland. It is well known that from the old 

 kingdom of Dalriada, in the north of Ireland, a colony settled in 

 Argyllshire, and gradually acquiring dominion over the whole of 

 Scotland, gave that kingdom its present name. I would therefore 

 propose that the term " Dalradian " might be adopted as an appro- 

 priate and useful appellation for the crystalline schists of the north 

 of Ireland and the centre and south-west of Scotland *. 



The special feature of this great metamorphic series which 

 requires notice on the present occasion is the evidence that, interca- 



* The adjective ought properly to be ' Dalriadan,' with the accent on the 

 second syllable ; but I feel compelled to alter it into a form more consonant 

 with English habits of pronunciation. 



I regret that I have found it impossible to apply to these rocks the term 

 ' Monian,' proposed by Professor Blake for the pre-Cambrian rocks of 

 Anglesey. In the first place, I disclaim any idea of founding a new geological 

 " system." Our knowledge of the rocks in question is still too vague for any 

 such ambitious effort, and, as I have said in the text, these rocks may include 

 representatives of Archaean gneiss, Torridon sandstone, Durness limestone, 

 possibly even of Lower-Silurian masses. In the second place, as I shall try to 

 show in the course of this Address, the ' Monian ' system includes Archaean 

 gneiss, younger schists like those which I class as Dalradian, and strata, volcanic 

 and fossiliferous, of undoubtedly Bala age. It would only aggravate this 

 confusion to apply the name to still another series of rocks in another and 

 distant area. My object is solely to provide a convenient descriptive epithet 

 which shall be precise and save periphrasis. 



