470 Notices of Memoirs — Dr. Jehu — Fossils from Aberfoijle. 



associated with a coarse basic igneous rock somewhat bresciated, as at 

 Maol Ruadh. These probably represent igneous intrusions. Near Loch 

 Lomond grits only are exposed. At the north-east end, near Callander, 

 the belt consists largely of grits, but at Kilmahog quarry there is 

 a good exposure of black shales with an interbedded limestone identical 

 in character with the limestone in the Margie Series described by 

 Mr. G. Barrow (Q.J.G.S., 1901). 



The belt in the Aberfoyle area emerges from under the Upper Old 

 Eed Sandstone north of Gualann and extends north-eastwards to a mile 

 north-east of Aberfoyle. Widest near Gualann — about half a mile. General 

 strike of beds north-east and south-west; general dip north-west, at high 

 angles. Beds often isoclinally folded along crush-planes striking north- 

 east and south-west. Apparent order of succession from below upwards 

 near Kelty Water : (1) Hornblendic and chloritic schists, probably 

 representing intrusive sheets ; (2) thin band of chert and black shale, 

 only traceable for about a mile ; (3) band of grit which as traced to 

 north-east comes to abut against Lower Old Eed crush rock ; (4) thicker 

 band of black shales and cherts ; (5) Grit. The Leny Grit follows on 

 the north-west, but at other places it appears to come directly on the 

 black shales and cherts. 



Difficulty in distinguishing the grits of the Boundary Fault Series 

 from the Leny Grits. The latter are generally greenish, the former 

 greyish and weathering yellowish-brown, and are peculiar in containing 

 fragments of black shale, chert, and vesicular volcanic matter. Lumps 

 and courses of a very dark grit also occur in the black shales. The shales 

 are usually black, carbonaceous, staining the fingers ; generally very 

 crushed. The chei-ts are pale grey to dark in colour, often finely banded 

 with frequent interleaves of black shale. Joints and veins at right 

 angles to the bedding often numerous. Thin cherty bands and nodules 

 often seen in the shales. Some of the rocks are a crushed mass of black 

 shale and cherty material. The beds are often distinctly brecciated. 



Remains of Radiolaria discovered by Dr. Peach some years ago in 

 cherts near Gualann. Recently a number of fossils have been found 

 in pale-grey chert bands, 1 to 3 inches thick, in an exposure on the 

 south-east side of the Bofrishlie Burn, about -100 yards north-west of 

 Arndrum. The fossils occur in muddy films in the chert. Belt 

 here only 300 to 350 feet wide. Some of the shales and cherts are 

 thrust over the disrupted edges of the bands which have yielded fossils. 

 A little north-west the cherts are brecciated, and courses of grit occur 

 in the black shales, also showing signs of brecciation. Some calcareous 

 bands occur in the shales in the bsd of the stream. The fossils are 

 almost all hingeless Brachiopods, and the following forms have been 

 determined by Dr. Peach : — • 



Acrotreta sp., Lingulella sp., ? Obohis s^., Obolella sp., also the 

 flattened chetse of Polychgete worms. 



The fossils indicate that the series is probably of Upper Cambrian age. 



IX. — On the Origin of some of the Mica-schists of Anglesey.' By 

 Edward Greenly. 



IN the south-east and centre of Anglesey extensive tracts of country 

 are occupied by mica-schists in which it is a very rare thing to find 

 any survival of the original structures. They are holocrystalline rocks, 

 usually with strong parallel structure, and composed essentially of 

 quartz, alkali-felspars, and a white mica. In certain compact varieties, 

 however, especially about Y Graig, Holland Arms, traces of felsitic 

 texture can be found. Dr. Teall, who has examined the rocks in 

 the field as well as under the microscope, regards them as in all 



^ Abstract of paper read before the British Association, Section C (Geology), 

 Dundee, September, 1912. 



