82 



NATURE 



\_May 26, 1 88 1 



will be seen on an inspection of this map that the quartzite 

 series is represented as terminating obliquely against the 

 margin of the granite or gneiss. This obliquity has never 

 (as far as I can discover) been explained. The prevalent 

 opinion seems to have been that the newer series has been 

 converted into the older by increased metamorphic action. 

 For some time past I never studied Griffith's map without 

 the impression that the obliquity was due to unconformity 

 of stratification, and on the determination of this point 

 plainly rested the question whether the granitoid gneiss 

 was, or was not, of Laurentian (or "Archaean") age. 



Having had the advantage of a visit to some of the sec- 

 tions in the North Highlands of Scotland, in company with 

 my colleague, Mr. R. G. Symes, under the able guidance 

 of Prof Geikie, last summer, I was in a position much 

 more favourable for undertaking the investigation of this 

 interesting question than would otherwise have been the 

 case ; and in the recent visit to Donegal I was accom- 

 panied by Mr. Symes and j\lr. Wilkinson, of the Irish 

 Survey, who rendered material aid in this preliminary 

 survey. 



The knowledge thus obtained has been of essential ser- 

 vice, and I am happy to be able to state that we have 

 succeeded in identifying the Donegal gneissic series, both 

 as regards its mineral characters and its unconformable 

 relations to the Lower Silurian series with the Laurentian 

 beds of Sutherland and Ross. The relations of the two 

 series in Donegal are similar to those which are to be ob- 

 served in the Laxford and Rhiconich districts, where the 

 Cambrian sandstones and conglomerates are absent, and 

 where, in consequence, the Lower Silurian quartzites and 

 limestones rest directly on the old gneiss These condi- 

 I "^, ' jT ,he clearly made out in the neighbourhood of 

 ougi salt, nea, o,^ where successive beds of quartzite, 

 Imiestone, diorite and sen,.. .. .u. , giluriin series 



termmate abruptly at the margin of the gii,,i.,„;, cpHes 

 We satisfied ourselves that this truncation of the Silurian 

 beds is not due to faulting, as there is no appearance of 

 disturbance or fracturing amongst the strata on either 

 side. Similar — though less clear — indications were observ- 

 able all along the eastern or southern margin of the 

 gneissose district. Nor was the unconformity confined to 

 the Silurian series, as we found that the beds of this forma- 

 tion came into contact with these of different geological 

 horizons amongst the gr.eissic series at different places; 

 there occurs, in fact, a double unconformity. 



When examining the gneissic scries we were often struck 

 by the resemblance presented by the beds to those of 

 Sutherlandshire, particularly amongst the lower portions. 

 The massive foliated rock formed of red orthoclase, 

 greyish oligoclase, green and black mica, and quartz, 

 traversed by pegmatite veins, is identical in character 

 with that from Rhiconich and Laxford ; while the upper 

 beds are interstratified with hornb'.endic and micaceous 

 schists like those near Scourie. The occurrence of thin 

 beds of white and grey marble, with sphene, idocrase, &c., 

 in the Laurentian gneiss, seems peculiar to the Irish 

 rocks, and brings them into close relationship with those 

 of Canada. 



A new basis has thus been formed for the whole super- 

 structure of the Irish geological formations as deeply 

 seated as that of any other country, and there can be 

 little doubt that as the Laurentian beds have thus been 

 recognised on the clearest evidence in Donegal, they 

 may be recognised also in parts of Sligo, Mayo, and 

 Galway, where the evidence is not so clear. 



As I hope to have an opportunity of more fully stating 

 the case at the forthcoming meeting of the British Asso- 

 ciation at York, it will be unnecessary here to enter on 

 further details. I will only add that in speaking of the 

 gneissic series as "Laurentian" I only wish it to be 

 understood that the beds are contemporaneous with those 

 underlying the Cambrian and Lower Silurian scries of 

 the Scottish Highlands. Whether they are really the 



representatives in time of the Laurentian beds of Canada 

 is immaterial for my present purpose. For my own part 

 I consider the preponderance of the evidence to be in 

 favour of the view that they are in the main repre- 

 sentative. Edward Hull 

 Geological Survey Office, Dublin 



JOSEPH BARNARD DA VIS 



AFTER a short illness Dr. J. Barnard Davis died last 

 week at his residence at Hanley, Staffordshire, 

 being about eighty years of age. In the summer of 1820, 

 while still a student, he made a voyage to the Arctic 

 regions in the capacity of surgeon to a whaling ship. In 

 1823 he became a licentiate of the Society of Apothe- 

 caries ; twenty years later he passed the College of 

 Surgeons, and in 1S62 took the M.D. degree of the Uni- 

 versity of St. Andrew's. In 1868 he was elected into the 

 Royal Society. Soon after obtaining his first qualification 

 he settled down in the Potteries, and but for what he 

 describes, in the preface to his " Thesaurus Craniorum," 

 as "an accidental conversation with a friend," might 

 have remained through life leading the useful but un- 

 eventful life of thousands of general practitioners in the 

 country, unknown beyond his immediate sphere of work. 

 That accidental conversation however lighted up some 

 smouldering embers of an interest which long before had 

 been kindled by the lectures of Lawrence on the 

 Natural History of Man, and led to the researches 

 which resulted in the publication (in conjunction with 

 the late Dr. Thurnam) of the " Crania Brit:.nnica," 

 or delineations and descriptions of the skulls of the 

 aboriginal and early inhabitants of the British Islands, 

 illustrated with si.xty-seven beautifully-executed litho- 

 graphic plates, completed in 1856. Besides this Dr. 

 Da%'is published manv memoirs on anthropological sub- 

 j^<,to_ including one " On Synostoiic Cr.ania among 

 Aboriginal Races of Man," one on " The Osteology of the 

 Tasmanians," one on " The Peculiar Crania of the In- 

 habitants of Certain Groups of Islands in the Western 

 Pacific," and one published in the PJiilosophical Trans- 

 actions for 1 868, " On the Weight of the Brain in different 

 Races of Man." 



But it was by his famous collection, rather than by his 

 writings, that Dr. Barnard Davis was best known, and 

 the time, labour, and money which he spent in gathering 

 it together is his greatest service to science. During a 

 long period of time, in which the national and other 

 public collections were losing the golden opportunities 

 afforded by the extension of English adventure and 

 commerce to all parts of the world, and allowing 

 races to die out or their characteristics to become 

 obliterated by intermixture with others. Dr. Davis let 

 no chance of procuring specimens pass by, and was 

 unwearied in his correspondence with travellers, col- 

 lectors, and residents in foreign lands. He thus amassed 

 together within a few rooms of a small house in Stafford- 

 shire a collection of crania and skeletons, nearly all 

 with carefully- recorded histories, far exceeding in size 

 that in all the public museums of the country put to- 

 gether, and only surpassed in very recent years by any of 

 the Continental collections. In 1S67 he published a 

 catalogue called " Thesaurus Craniorum," which not only 

 contains a description and many figures of the specimens, 

 with 25,000 measurements, but which is also a perfect 

 storehouse of information, owing to the literary references 

 with which it abounds. The publication of this catalogue 

 made the collection so well known that it naturally led to 

 its increase, and in 1875 '' became necessary to publish 

 a supplement on the same plan, in which the history of 

 the literature of the subject was continued to date. The 

 catalogue and supplement contain descriptions of more 

 than 1700 specimens, mostly crania. 



Warned by failing health and increasing years of the 



