The fine-grained granite that occurs in dykes is called elvan, which, if easiest to work, is most liable to decay. In Cornwall the elvan of Pentewan was used for the fine church of S. Austell, and as a consequence the weather has gnawed it away, and the greater part has had to be renewed. On the other hand, the splendid elvan of Haute Vienne has supplied the cathedral of Limoges with a fine-grained material that has been carved like lace, and lasts well.
The drift that swept over the land would appear to have been from west to east, with a trend to the south, as no granite has been transported, except in the river-beds to the north or west, whereas blocks have been conveyed eastward. This is in accordance with what is shown by the long ridges of clay on the west of Dartmoor, formed of the rubbing down of the slaty rocks that lie north and north-west. These bands all run north and south on the sides of hills, and in draining processes they have to be pierced from east to west. This indicates that at some period during the Glacial Age there was a wash of water from the north-west over Devon, depositing clay and transporting granite.
On the sides of the tors are what are locally termed "clitters" or "clatters" (Welsh clechr), consisting of a vast quantity of stone strewn in streams from the tors, spreading out fanlike on the slopes. These are the wreckage of the tor when far higher than it is now, i. e. of the harder portions that have not been dissolved and swept away.
"The tors – Nature's towers – are huge masses of granite on the top of the hills, which are not high enough to be called mountains, piled one upon another in Nature's own fantastic way. There may be a tor, or a group of tors, crowning an eminence, but the effect, either near or afar, is to give the hilltop a grand and imposing look. These large blocks of granite, poised on one another, some appearing as if they must fall, others piled with curious regularity – considering they are Nature's work – are the prominent features in a Dartmoor landscape, and, wild as parts of Dartmoor are, the tors add a notable picturesque effect to the scene. There are very fine tors on the western side of the moor. Those on the east and south are not so fine as those on the north and west. In the centre of the moor there are also fine tors. They are, in fact, very numerous, for nearly every little hill has its granite cap, which is a tor, and every tor has its name. Some of the high hills that are tor-less are called beacons, and were doubtless used as signal beacons in times gone by. As the tors are not grouped or built with any design by Nature to attract the eye of man, they are the more attractive on that account, and one of their consequent peculiarities is that from different points of view they never appear the same. There can be no sameness in a landscape of tors when every tor changes its features according to the point of view from which you look at it. Every tor also has its heap of rock at its feet, some of them very striking jumbles of blocks of granite scattered in great confusion between the tor and the foot of the hill. Fur Tor, which is in the very wildest spot on Dartmoor, and is one of the leading tors, has a clitter of rocks on its western side as remarkable as the tor itself; Mis Tor, also on its western side, has a very fine clitter of granite; Leather Tor stands on the top of a mass of granite rocks on its east and south sides; and Hen Tor, on the south quarter, is surrounded with blocks of granite, with a hollow like the crater of a volcano, as if they had been thrown up by a great convulsion of Nature. Hen Tor is remarkable chiefly for this wonderful mass of granite blocks strewn around it. All the moor has granite boulders scattered about, but they accumulate at the feet of the tors as if for their support."3
Here among the clitters, where they form caves, a search may be made for the beautiful moss Schistostega osmundacea. It has a metallic lustre like green gold, and on entering a dark place under rocks, the ground seems to be blazing with gold. In Germany the Fichtel Gebirge are of granite, and the Luchsen Berg is so called because there in the hollow under the rocks grew abundance of the moss glittering like the eyes of a lynx. The authorities of Alexanderbad have had to rail in the grottoes to prevent the gold moss from being carried off by the curious. Murray says of these retreats of the luminous moss: —
"The wonder of the place is the beautiful phosphorescence which is seen in the crannies of the rocks, and which appears and disappears according to the position of the spectator. This it is which has given rise to the fairy tales of gold and gems with which the gnomes and cobolds tantalise the poor peasants. The light resembles that of glow-worms; or, if compared to a precious stone, it is something between a chrysolite and a cat's-eye, but shining with a more metallic lustre. On picking up some of it, and bringing it to the light, nothing is found but dirt."
Professor Lloyd found that the luminous appearance was due to the presence of small crystals in the structure which reflect the light. Coleridge says: —
"'Tis said in Summer's evening hour,
Flashes the golden-coloured flower,
A fair electric light."
In 1843, when the luminosity of plants was recorded in the Proceedings of the British Association, Mr. Babington mentioned having seen in the south of England a peculiar bright appearance produced by the presence of the Schistostega pennata, a little moss which inhabited caverns and dark places: but this was objected to on the ground that the plant reflected light, and did not give it off in phosphorescence.4
When lighted on, it has the appearance of a handful of emeralds or aqua marine thrown into a dark hole, and is frequently associated with the bright green liverwort. Parfitt, in his Moss Flora of Devon, gives it as osmundacea, not as pennata. It was first discovered in Britain by a Mr. Newberry, on the road from Zeal to South Tawton; it is, however, to be found in a good many places, as Hound Tor, Widdecombe, Leather Tor, and in the Swincombe valley, also in a cave under Lynx Tor. If found, please to leave alone. Gathered it is invisible; the hand or knife brings away only mud.
But what all are welcome to go after is that which is abundant on every moorside – but nowhere finer than on such as have not been subjected to periodical "swaling" or burning. I refer to the whortleberry. This delicious fruit, eaten with Devonshire cream, is indeed a delicacy. A gentleman from London was visiting me one day. As he was fond of good things, I gave him whortleberry and cream. He ate it in dead silence, then leaned back in his chair, looked at me with eyes full of feeling, and said, "I am thankful that I have lived to this day."
The whortleberry is a good deal used in the south of France for the adulteration and colouring of claret, whole truck-loads being imported from Germany.
There is an interesting usage in my parish, and I presume the same exists in others. On one day in summer, when the "whorts" are ripe, the mothers unite to hire waggons of the farmers, or borrow them, and go forth with their little ones to the moor. They spend the day gathering the berries, and light their fires, form their camp, and have their meals together, returning late in the evening, very sunburnt, with very purple mouths, very tired maybe, but vastly happy, and with sufficient fruit to sell to pay all expenses and leave something over.
If the reader would know what minerals are found on Dartmoor he must go elsewhere.
I have a list before me that begins thus: "Allophane, actinolite, achroite, andalusite, apatite" – but I can copy out no more. I have often found appetite on Dartmoor, but have not the slightest suspicion as to what is apatite. The list winds up with wolfram, about which I can say something. Wolfram is a mineral very generally found along with tin, and that is just the "cussedness" of it, for it spoils tin.
When tin ore is melted at a good peat fire, out runs a silver streak of metal. This is brittle as glass, because of the wolfram in it. To get rid of the wolfram the whole has to be roasted, and the operation is delicate, and must have bothered our forefathers considerably. By means of this second process the wolfram, or tungsten as it is also called, is got rid of.
Now, it is a curious fact that the tin of Dartmoor is of extraordinary purity; it has little or none of this abominable wolfram associated with it, so that it is by no means improbable that the value of tin as a metal was discovered on Dartmoor, or in some as yet unknown region where it is equally unalloyed.
In Cornwall all the tin is mixed