numerous sick who resorted thither, I could not but be convinced of its cleansing and healing quality in divers inveterate and rebellious. eruptions on the skin; and in some scald heads; and in many old stubborn ulcers, which had baffled the common methods of use."

This account of the Irish bog waters has a curious resemblance to Dr. Short's account of the Askern water. The Irish waters probably contain a higher proportion of peaty matter than the Askern waters, but are free from sulphuretted hydrogen, and contain only very small quantities of calcium and magnesium salts.

A POOL THAT NEVER FREEZES.

About 120 yards to the south of the Askern Pool is an irregularly shaped piece of water about 100 yards long and 55 yards across at the widest part. It is known locally as the Mather or Madder Pool or Pits, and is shown under that name on the 6-inch Ordnance Survey Map. So far as I could learn it is of no great depth, and it communicates by narrow drains with the large drains that intersect the Common.

This pool has never been frozen over in the memory of anyone living in the neighbourhood, and there is a local tradition that it never has been frozen.

During the severe winter of 1890-91 the Askern Pool was covered with a thick sheet of ice, but the Mather Pool, although close by, showed no traces of ice even in the shallow water at the edge. On January 17th, 1891, after the frost had continued unbroken for weeks, the temperature of the air was 1·5° C. (29·3 F.), and the Pool, as already stated, was covered with a thick sheet of ice and had been so covered for days, and the temperature of the water drawn from the Mather Close Well was 4.8° C. (406 F.), yet the temperature of the water of the Mather Pool, about three feet from the edge and where it was still quite shallow, was as high as 90° C. (48° F).

This water contains magnesium and calcium sulphates and calcium carbonate, together with dissolved peaty matter, but without any sulphuretted hydrogen. There is nothing in the position or surroundings of the Mather Pool to explain its peculiar behaviour, and it would probably repay investigation.

I cannot conclude this paper without expressing my great indebtedness to my friend Dr. J. G. Cassels, of Askern, for his ever ready assistance, both in the work at the wells and in the enquiry into the history of the spring. I am also indebted to the proprietors of the various Pump Rooms for the facilities they so readily gave me for collecting the samples of water and making experiments at the wells.

THE EFFECT OF FAULTS ON THE CHARACTER OF THE SEASHORE.

BY THEO. T. GROOM, F. G.S.

(Read January 16th, 1894.)

If the shore-line extending from Westward Ho near Bideford to a point situated about a mile to the south-west, and forming the central strip of Barnstaple Bay, be viewed broadly, it will be seen to take a tolerably even and unbroken course; when examined in detail, however, it is found to be broken up at all levels of the tide into a series of small bays and promontories, or islands (figs. 1 and 2). From the cliffs which bound the shore abruptly on the inland side a rocky platform, generally from two to three hundred yards wide, slopes gently down to the irregular low-water line. The cliffs usually vary in height from 15 or 20 feet above high-water level to perhaps five or six times that height, and show at a relatively small height above high-tide mark (20 feet or so) the remains of an old pebble-beach; this, so far as it is preserved, shows no trace of the differential movements which have affected the rocks of the intertidal platform. The facts given above indicate that since the elevation which raised the old beach the land here has remained stationary for a period long enough to allow of the formation of a considerable indentation of the profile along the shore-line, and that, as might be expected, the differential movements which have affected the platform and which will be referred to later, are of earlier date than the formation of the old beach.

The rocks forming the platform and the cliffs are a series of shales, sandy shales, flags and sandstones, belonging apparently to the Morchard and Exeter types recognised by Mr. W. A. E. Ussher* in the Culm Measures. These, as is well known, have been affected by folds running chiefly E. and W., so that the rocks strike nearly straight out to sea. In the area examined they dip sometimes to

* The Culm Measures of Devonshire. Geol. Mag., vol. iv., 1887. The British Culm Measures. Proc. Somerset Archæological and Natural History Society, vol. xxxviii., 1892.

the north, and sometimes to the south, at an angle of about 60° or more (figs. 1 and 2). A first glimpse of the platform from the summit of the cliff shows in some places what appears to be a jumble of high jagged barnacle-covered rocks, interspersed with smooth and flat areas often covered with fucoids. As one walks along the cliff

a grouping of these elements becomes very evident; the higher and more rocky portions are seen to form bands or blocks separated by wider zones of the smoother rocks (figs. 4 and 5).* A striking feature which soon becomes apparent is that numerous definite channels intersect in a conspicuous manner these rocks in all directions, the main ones crossing or bounding rough and smooth areas alike (figs. 1, 3, 3a, 4). These channels are so prominent that many of them have been mapped by the Survey, and are well shown on the six-inch maps of the district. They are either permanently or temporarily filled with water. Some are clearly related to the direction and configuration of the coast (cf. figs. and maps). Upon examination they are seen in most cases to mark lines of faulting. The appearances at once suggested comparison on a small scale with the state of things described by the Scandinavian geologists along the coast of Norway, where the fjords have been shown, notably by Kjerulf and Brögger,† to have a close relation with the faults of the district. Fig. 1 shows the fjordlike character of many of the small inlets of a portion of the coast. I became wishful, therefore, to ascertain whether the configuration of the coast in this locality was due at all directly to crust-movements, or solely to denudation, and to trace the effect of faulting on the character of the shore, more especially since this is not mentioned by De la Beche in his account of the denudation of this coast.

If the smoother and lower and the relatively elevated and rocky portions of the platform be compared, it is found that the former consist of blue shales and flags, whilst the latter are composed of hard bands of well-jointed greyish blue compact sandstone. The sandstones and flags are everywhere more or less divided up by isolated bands of shale, and the shales by thin bands of sandstone. The

I am indebted to the kindness of my brothers, Messrs. P. and W. Groom, for the photographs reproduced in this paper.

+ Die Bildungsgeschichte des Kristianiafjordes. Nyt Magazin for

Naturvidenskaberne xxx., 1886.

included shale bands tend to form channels, and the sandstones minor ridges of varying breadth and distinctness, running out to sea. Observation makes it clear that the existence of the relatively more and less elevated portions of the platform is due simply to the different rates at which denudation has taken place (the softer irregularlybroken beds being reduced to a lower level), and not in any way to the elevation or depression of faulted-blocks; this will also be evident from a consideration of the nature of the dislocations.

The channels, which intersect the rocks at varying angles are of some interest from the light thrown by them upon the effect of faults in facilitating marine denudation, and in modifying the configuration of the coast. When they are examined in detail they are seen to traverse nearly the whole of the platform between tidemarks; towards high-tide mark they generally become less marked or slight, and the fault itself is often distinguishable only by a careful examination of the disposition of the strata on either side; towards the sea they become wider and deeper, and form conspicuous fjordlike inlets (figs. 3, 3a), the lower parts of which are permanently filled with water. Still farther out to sea, they cut up the elevated sandstone reefs into small islets, separated from one another, and from the main land by channels of some depth (fig. 4). The channelforming faults occur both as dip and strike faults, but faults crossing the outcrop of the beds obliquely are by far the most important. By the combined action of these faults the whole of the inter-tidal platform is cut up into a pavement, or mosaic. of angular blocks, the sandstone portions of which project above the level of the rest as ridges, blocks, or islets.

The smallest faults are planes of slight dislocation, along which the sea-water with its particles of sand can erode. In many cases the erosive action is facilitated by the irregular bending of the folia of the shale at the margin of the fault, so as to produce an easilyremoved fringe of material. In the case of the larger faults the dragging action due to the horizontal displacement has produced, not a simple fringe, but a fringe traversed by lines, along which shearing or fracture parallel to the direction of the fault, has occurred. In many cases no definite fringe is formed, but planes of separation,