Southern Arm Research Articles

XI. Reported Metamorphic Zone at Castlefern

The contact metamorphism of the Ordovician rocks around the granites of Kirkcudbrightshire has long been well known and is distinct around each of these intrusions. South-west of Moniaive is recorded on the Geological Survey Map of Scotland, sheet 9 1874, a “zone of metamorphosed rocks” as extending on the northern side of the Castlefern Water from a little west of Castlefern Farm for four miles to below Glencrosh at the foot of Kirkcudbright Hill. The trend of this zone is approximately west-south-west to east-north-east. It is parallel to the general strike of the sedimentary rocks in the district, but is transverse to the general trend of the granitic intrusions. It is referred to in the Memoir of the Geological Survey in explanation of that sheet (No. 9, 1877, p. 22) as the schistose area from Craigneston Hill eastward to Moniaive. Craigneston Hill is about a mile east of Castlefern. The granites of the western part of the Southern Uplands are arranged as a horse-shoe with the open end facing east-north-east. The northern arm includes the granites of Spango and Carsphairn; the western line consists of the granite of Loch Doon and the Merrick, and the massif from Cairnsmore of Fleet to Loch Ken; the southern arm extends from Auchencairn to Criffell. This “metamorphosed zone” near Moniaive suggested the occurrence of granite at a slight depth below the surface. Such an intrusion might be a member of this Loch Doon-Criffell chain, the plan of which it would alter from a horse-shoe This 250-word extract was created in the absence of an abstract

Mortlakes as a Cause of River-windings

MORTLAKE on the Thames has a place-name which not only accords with the natural history of the place, but also supplies a word which might conveniently be brought into common use to signify a process which plays an important part in the development of every river system, just as the River Meander supplies a word to signify the windings of any river. The area between Barnes and the Thames was formerly an island in the river (Fig. 1), formed by a division of the stream into a northern and a southern arm reunited at the down-stream ends. The southern arm is now incomplete; the part of it remaining is included in the line of the Beverley Brook, which, having come from the south, turns to the east round a bold curve and joins the Thames. This leaves a gap between the convexity of the curve and the river at the point where it previously divided. This gap now forms the isthmus of a peninsula into which the island has been converted by the partial effacement of the southern arm of the divided river. Here Mortlake stands. It is on or near to the former line of the stream which has been in part effaced. This part has become a dead stream—a mortlake, the word “lake” having been used in the Middle English sense as signifying a stream. Leland the Ghronicler wrote that “there runneth a praty lake out of Sudeley Parke down by the Gastle and runneth into Essebourne Brook at the south syde of Winchcombe.” And again: “I passed over 2. or 3. small lakes betwixt Chiltinham and Gloucester and they resort to Severne.” The word is still used in some places as meaning a stream; children on the Severn banks still sing of the moon as claiming to guide the ship “up the lake.”

On the New Red Sandstone of Nova Scotia

In several late papers on the carboniferous rocks of Nova Scotia, reference has been made to a deposit of red sandstone skirting the shores of Cobequid Bay, and resting unconformably on strata of the carboniferous system. I propose in the present paper, to describe this formation as it occurs in the above-named locality, and in other parts of the country bordering the southern arm of the Bay of Fundy, retaining provisionally the name of New Red Sandstone, which is at least locally appropriate. The new red sandstone of Nova Scotia has already been described by Messrs. Jackson and Alger, and by Dr. Gesner. The attention of these geologists was however directed rather to the structure of the trap, and to the numerous crystallized minerals which it contains, than to the geological relations of the deposit; and they did not distinguish it from a group of sandstones, with beds of limestone and gypsum, occurring in its vicinity, which has since been shown by Mr. Lyell to belong to the carboniferous system.