712 KEPOKT— 1892. 



A middle sub-zone of green chert. 



A lower sub-zone of red and chocolate-coloured chert and jasper. 



The chert beds or nodules are separated from each other by the finest sediment, 

 and towards the bottom of the zone by tuft' and agglomerate, the latter con- 

 taining angular fragments of radiolariau chert. The zone reposes on a platform of 

 basic lavas and agglomerates. It is seen on the crests of anticlines over an area of 

 from 2,000 to 3,000 square miles of the northern half of the ujjlands, and, in all 

 probability, has a much greater extension though hidden under newer sediments. 



From the chert Dr. Hinde has described in the ' Ann. Mag. Nat. Hist.' for July, 

 1890, twenty-three species of radiolaria. 



This deposit is regarded by the author as a true radiolariau ooze. When traced 

 from south to north the upper zones become in turn replaced by sediment, thus 

 beha\'ing in the same manner as the Moffat black shales, and indicating that the 

 land whence these sediments proceeded lay to the north of what are now the 

 Southern Uplands. 



2. On the Contact Metamorpliism of the Hadiolarian Chert in the Lower 

 Sihirian Rochs along the Margin of the Loch Domi, Granite. By 3. 

 HoRNE, F.G.S., of H.il. Geological Survey of Scotland. 



[Communicated by permission of the Director-General.] 



While tracing the representatives of the Moffat series m the neighbourhood of 

 Loch Doon, during the present summer, certain remarkable features were noted 

 by me in the radiolariau chert when followed along the outcrop to the pomt of 

 junction with the granite. About two miles from the igneous mass the chert pre- 

 sents features similar to those in the unaltered areas between Abington and Lead- 

 burn, About a mile from the junction the chert becomes slightly granulitic, and 

 the radiolaria are not so discernible with the pocket lens ; while tbe graptolites in 

 the adjoining black shales are quite fresh and determinable. About half a mile 

 from the margin of tbe granite the chert has been completely granulitised, and yet 

 the radiolaria are still traceable in the matrix. At this stage there is a slight 

 development of mica. Close to the granite the chert has undergone a complete 

 transformation ; the rock has been recrystallised, consisting of large quartz grains 

 with irregular edges, remarkable for the number of inclusions. Biotite is largely 

 developed as rounded inclusions in the quartz granules. 



3. On the ' Grampian Series ' (Pre-Camhrian Bocks) of the Central 

 Highlands. By Henry Hicks, M.D., F.li.S., Sec. of the Geol. Soc. 



In his address to the Geologists' Association in the year 1883 (' Proceedings 

 of the Geologists' Association,' vol. viii. p. 270) the author gave the name of 

 'Grampian series' to a group of rocks which occupy an extensive area in the 

 Central Highlands. He described them briefly as ' tender gneisses, bright siliceous 

 schists, chiastolite schists, quartzites and limestones,' also some 'chloritic schists.' 

 He classed them as of pre-Cambrian age, and all the evidence since obtained 

 tends to confirm this view. It is quite possible, of course, that newer rocks may 

 be in places entangled amongst them, but the majority of those which he claimed 

 as being of pre-Cambrian age are now generally admitted to be older than any of 

 the Palpeozoic rocks of that area. The further descriptions of these rocks now 

 given have been prepared with the kind assistance of Professor T. G. Bonney, D.Sc, 

 F.R.S., to whom the author some time since submitted specimens, collected at 

 various points in the year 1880. 



From Near Ballachulish, S)-c. A finely banded, fine-grained micaceous schist, 

 containing apparently a considerable amount of felspathic matter. 



From Glen Sjoean, S,c. Fine-grained gneisses, not rich in quartz, but with a 

 considerable amount of black mica, not markedly foliated except as the result of 

 subsequent pressure. All are characterised by a peculiar speckled aspect, the 

 spots being about the size of pins' heads'. The felspar varies from a warm to a 

 reddish grey. 



