ON ERRATIC BLOCKS OF THE BRITISH ISLES. 253 



A visit paid by the Yorkshire Geological and Polytechnic Society to 

 the Tweed Valley two years ago enabled members of the Yorkshire 

 Boulder Committee to acquire a' familiarity with some of the distinctive 

 rocks of that region, with the result that the Haggis Rock, so well known 

 to Scottish geologists, is reported from several localities in the east of 



Yorkshire. . . , i- i i i 



The interest of these observations is, however, eclipsed by a remark- 

 able series of boulders noted by Mr. H. B. Muff, now of the Geological 

 Survey of Scotland. Mr. Muff submitted to his colleagues, Messrs. 

 B N Peach and E. H. Cunningham-Craig, a series of specimens of boulders 

 from the country round Whitby, and among them were recognised rocks 

 from the Southern Uplands of Scotland, such as Haggis Rock, Queens- 

 bury grits, and radiolarian chert ; Old Red Sandstone conglomerate of 

 a Scottish type and various volcanic rocks of which the source may be 

 in either the Cheviots, Pentlands, or Ochills. The authorities quoted con- 

 sider that it is unsafe to assign porphyrites specifically to the Cheviots, 

 as rocks of the same petrological character occur as far north_ as the 

 Ochills The succeeding determinations show that there is no improb- 

 ability in this suggestion, for they include a large suite of quite distinctive 

 Highland rocks, namely, Leny grits, Highland schists of Perthshire, 

 Molne schists, and Ben Ledi grits. _ ^ , o i- • 



Additional localities in Yorkshire are given for the Scandinavian 

 rhomb porphyries, augite- and zircon-syenites, and the Secretary, 

 Mr Howarth, records a rock resembling the peculiar nodular gabbro of 

 Imensfis, near Grimstad. A very satisfactory identification is that _ by 

 Mr Sta'ther of a boulder absolutely identical in structure and constitu- 

 tion with the elfeolite syenite (foyaite) of Kvelle, near Larvik. 



It is gratifying to be able to announce at this meeting the resumption 

 of its work by the Belfast Naturalists' Field Club. In past years 

 (1895 and 1896) this society contributed most valuable and interesting 

 reports to the Committee, and it is to be hoped that other organisations 

 in Ireland will follow its example. The most noteworthy facts in the 

 present report are, first, the very wide and general dispersal of the well- 

 known riebeckite-eurite of Ailsa Craig. Out of forty localities which 

 are mentioned in the Belfast society's lists no fewer than twenty-six 

 have yielded this rock. The schedules, carefully compiled by Madame 

 Christen and now presented, give in a condensed and convenient form 

 the results of a large amount of patient and minute research, and might 

 well be adopted as a model by any societies undertaking a survey of the 

 erratic blocks and allied phenomena of a new field of study. 



An appeal will be issued In the coming year to the Scottish societies to 

 take up the work of observing and recording the erratics of the country, 

 so that at least their general distribution may be roughed out. Dr. John 

 Home has promised his active co-operation in the determination of the 

 sources of boulders observed. 



An observation made at Dunbar during the present summer 

 emphasises the necessity for guarding against the inclusion in lists of 

 erratics of stones which have been transported by human agency. A 

 block of zircon-syenite bearing a resemblance to a rock found at Larvik 

 in Norway was found upon the beach ; a specimen was submitted to the 

 officers of the Geological Survey at Edinburgh, and their opinion was 

 unanimous that it was not a Scottish rock. Renewed search was made 

 at Dunbar, which resulted in the discovery of twenty or thirty small 



