TRANSACTIONS OF SECTION C. 



639 



Donegal. 



Profound wiconformahility. 

 Teeeane No. IV. (Ordovician.) 



1. Basement stratum mullaghsaw- 

 nite, a firm conglomerate, in part arkose. 



2. Raphoe limestones and shales. 



3. Slates with irregular masses and 

 beds of sandstones, partly arkose. These 

 sandstones, sometimes pebbly, have re- 

 gular oblique systems of joining. Usually 

 these joints are so close together as to 

 give the rocks the appearance of piles 

 of huge books. 



Galway and Mayo. 



Prohahle unconformahility concealed 

 under the Killary and pantry Silurians. 



1. Basement beds unknown. 



2. Shales, slates, and grits with, in 

 places, Ordovician fossils. 



3. Massive grits. 



1, but 



4. Shales like those in No. 

 sub-metaniorphosed. 



5. Shot conglomerate. 



6. Sandstoneswith irregular thin beds 

 and pantry of a friable pebbly rock. 



7. Dark slate. 



The Lougli Keel series, No. 3, Terrane III., is the upper portion of the Millford 

 series, pushed into its present position by an overthriist : it is separated from the 

 Killygarvan volcanic series by a master fault. Between the series 4 and 5, 

 Terrane IV. (Gahvay and Mayo), there may be an unconformability, and the shot 

 conglomerate may be the equivalent of tlie mullaghsawnite of the co. Donegal ; a 

 break here, however, was not proved. The only series in the Terranes in both 

 columns, the age of which lias been proved by their fossils, are those numbered 

 2, 3, and 4 in the counties Galway and Mayo : these are the equivalents of the 

 Ordovician. 



Dawson in his address to the Geological Section at Toronto states his disbelief 

 in the basement comple.v. A. C. Lawson, in his paper ' On Internal Eolation and 

 Taxonomy of the Archean of Central Canada' (1890), seems to be of a similar 

 opinioH ; while Van Hise in his writings only gives a lialf-hearted consent ; the 

 writer finds it hard to believe in it. The section of the Laurentians shown in the 

 cliffs of the Saguenay Fiord is said to be a typical one ; and here, between the 

 river St. Lawrence and the Labradorian of St. John, there are various changes — • 

 foliated granite, granitic gneiss, felspathic varieties, and quartzitic varieties— that 

 would seem to suggest that the rocks were not one basement complex, but that 

 they had been supplied from zones of distinct magmas as long ago suggested by 

 Delesse. Then we come to the Labradorians of St. John. These in aspect are most 

 ancient, the foliation being extraordinary, so as not to be believed in except seen, 

 some of the measured leaves of quartz and felspar being from 9 to 12 ft. and 

 more long. Yet on examination this rock in its present position is younger than 

 the Laurentians, being intruded and sending apophyses into it ; but in its original 

 place it must be older. If the Laurentian is the basement complex, what is the 

 age of the Norian, and what is its genesis ? Similarly in Scotland and Ireland. 

 If the Lewisan or fundamental gneiss is Laurentian or basement complex, what is 

 tlie age of the granites and granitic gneiss with their apophyses ? Then there is 

 the 'Old Bay' of Scotland, called hornblende rocks in Ireland: what is its age and 

 genesis ? Some, at least, of the Scotsmen say that the Lewisan gneiss is the torn- 

 up ' Old Bay.' ^ If so, how did it exist to be torn iip into the hasemeyit complex ? 

 Then there are the quartzitic and highly felspathic varieties of the Lewisan that 

 are said to have their origin in masses of those classes of rocks. These are com- 

 plications that some people may understand, but others do not see their way 

 to believe that fundamental eocks uad theib oeigin in peefundamental 



ANCESTOBS. 



' There is a vein of humour in this Scotch sobriquet. The rock is the ' Old Bay,' 

 and yet it is to be torn up for the making of the oldest rocks on the face of creation. 



