426 MR. EDWARD GREENLY ON THE [Aug. 1992, 
(i). The typical jasper is a very hard, brittle, bright blood-red 
rock, compact, and with irregular fracture, and often traversed by 
a large number of small quartz-veins. It possesses often a mottled 
texture, which gives, under the hand-lens, an appearance strongly 
suggestive of the presence of organic remains. But nothing cer- 
tainly organic has yet been found in it. Some specimens have the 
oneal; 
~ . = 
Careg Onen? parr Aa 
qs: 
\ 
Index-Map of 
SOUTH-EASTERN ANGLESEY. 
SCALE =4 MILES TO 1 INCH, 
Red Wharf 
Bay 
eT 
= WDE 
ESS OS 
i 
N 
> Bridge 
1D.PATULUS BEDS 
Carboniferous... 2. = 
Ordovician 
Careg Onen and 
Bangor Rocks &c ..— 
Newborough and 
SPeiiGlelly ROG Sse 
Schistose Rocks of 
ser -— ay, 
iy 7 
SS 
© In ay ; = 
~ ) Caernarvon Beaumaris Are A ------ WZ 
— = — = 
ri i 
Holocrystalline Schists .... 
[The outcrop of Careg Onen Rocks at Careg Onen itself and the outcrops of 
the jaspers occupy areas of too limited an extent to permit of their being 
shown in the above map. | 
aspect of red breccias, cemented by clear quartz. Many are definitely 
spherulitic. A thin slice shows a mosaic of quartz-grains which at 
first appear to have rather evenly rounded outlines, but on careful 
scrutiny between crossed nicols they show re-entering curves along 
which the grains interlock with each other. The mottling visible 
with the hand-lens is seen to be due to aggregations of haematite-dust, 
round about which the quartz is clear and nearly free from inclusions. 
Each of the aggregates is situated in the middle of a quartz-grain, 
