myosucoides (on birch), Ulota phyllantha, Hypnum cupressiforme and Brachythecium rutabulum. These trees seem to be much more affected by the humid climate than such exotics as Escallonia, Ceanothus, Verbena and Mimosa (Acacia) which grow luxuriantly. This is one aspect of Colonsay, but there are also its sedgy and heathery moors like those of many another island of the West, and at the southern tip, where the Atlantic has full play over the Torridonian and mudstone slabs gently rising from the sea to make platforms and pools near the tide level, the Atlantic grey seal breeds in fair numbers. Elsewhere, on the cliffs, kittiwakes, razorbills and guillemots breed; and there are three species of tern, arctic, common and little, breeding on the island.
Colonsay and Oronsay together might well be looked upon as an epitome of the West Highland world in its full range and consequences of Atlantic exposure and sheltered mildness.
Farther to the north-west are Coll and Tiree, two more islands which receive practically the full force of the Atlantic, but which show decided differences in natural history. Tiree is very low indeed. The rocky portion of the island, of Lewisian gneiss, reaches its highest point in Ben Hynish, 460 feet, but by far the greater part of Tiree (Plate 25) is but a few feet above sea level and composed of blown shell sand resting on a platform of gneiss. The island is one of good-sized arable crofts and is so far different from most West Highland districts that it has a Clydesdale horse-breeding society of its own. The sandy pastures of Tiree are deficient in cobalt but recent researches in mineral nutrition of animals have allowed the farmers of Tiree to dress the land with as little as 2 lbs. an acre of a cobalt salt and prevent the onset of pine in sheep. The island has particular interest for the birdwatcher: first, it is on a migration route and gets both summer and winter visitors which would not be seen anywhere in the North Minch, and its rich arable land also attracts a large number and variety of birds. Loch Vasapol of Tiree is a famous place for various duck. Tufted duck breed there and the gadwall is found there in winter though so uncommon elsewhere in the West. The vast beaches encourage certain waders, including the bar-tailed godwit, sanderling and greenshank. In the past the snipe-shooting was reckoned the best in Europe. Happily, there is less of it now.
Glacial action in Tiree is shown by the Ringing Stone, a huge rounded boulder of augite which probably came to rest there after a journey in the ice from Rum. The stone is marked by many ringed hollows on its surface.
The island of Coll, once one is within it, reminds one of the low gneiss country of Sutherland. Here the innumerable little hills are still smaller than in Sutherland and not so steep, none rising above 339 feet. The island presents a uniform rocky appearance when seen from a distance on the east side. On the west side of Coll are miles of shell-sand dunes, a feature which tends to be characteristic of many of the islands which meet the full force of the Atlantic and are low enough to have allowed the sand preliminary lodgment. The interior of Coll is just peat where it is not bare gneiss, yet with its western pastures it has always had the reputation of being a good place for cheese and sound dairy cattle. This island is important for the student, of distribution of plants in relation to the last glaciation and associated changed ocean levels.
The low, sandy islet of Gunna lies between Coll and Tiree. It is a great place for Sandwich, common and arctic terns and I believe the little tern nests there too. Such burrowers as the sheld-duck are plentiful, of course. Barnacle and grey lag geese are common in winter.
The small group of tertiary basalt islands known as the Treshnish Isles lie between Coll and Mull. The most southerly one has a rounded cone of an old volcano, 284 feet high, which gives the island the name of Dutchman’s Cap (Plate Va). The middle island of the group, Lunga, also has a volcanic mound rising to 337 feet, but the other small islands are all flat-topped with sheer sides of amorphous basalt resting on a platform of lava. This platform is of great importance in the natural history of the Inner Hebrides because it makes a breeding ground for the Atlantic grey seal. The Treshnish group, especially the Harp Rock of Lunga (Plate XIXa), is a nesting place of kittiwakes and auks and fulmars. Storm petrels nest in the Treshnish also, and the Manx shearwater on Lunga at least. The quality of grass on these islands is excellent and attracts a vast flock of barnacle geese in winter. The green rich grass of the islands is reflected again in the presence of large mixed flocks of starlings and peewits. In winter-time hundreds of blackbirds and a good many thrushes live on the Treshnish group. Lunga, being infested with thousands of rabbits, has a stock of seven buzzards.
The Cruachan of Lunga will be a good place to rest for a few moments and look at the topography of Mull, that very interesting member of the Inner Hebrides, Mull of the Mountains as the Gael calls it. The eye is first struck by the shapely peak of Ben More, 3,169 feet. This is the highest point reached by the tertiary basalt in Scotland. The cone itself is the result of great weathering, and the various beds of this amorphous lava are evident now in the truncated edges of the lower slopes of the hill. For sheer hard going, the descent from the summit to Loch Scridain takes a lot of beating, for the traveller is constantly having to make his way round these faces of rock which are not readily obvious to him as he comes down the hill. The terraced quality of Mull is obvious in a large part of Loch Scridain, the terraces being exactly the same height on either side. The peninsula between Loch Scridain and Loch na Keal reaches on the north side a stretch of some miles of very fine cliffs with sweeping talus slopes at their foot. The cliffs of Balmeanach are to my mind one of the striking features of Mull. The 1,600-foot basalt cliffs have trapped the cretaceous sandstone layer beneath them. The cretaceous sandstone—the local representative of the chalk—may be found in a narrow stratum just above sea level. These cliffs are difficult to explore and remain largely unexplored. Down below, the small island of Inchkenneth, the burial place of old Scottish kings and chieftains, is also composed of low strata of this cretaceous sandstone. If there is anywhere where chimneys must have cowls it is on Inchkenneth, for the down draughts from the great cliffs in a south wind are tremendous. Slates have to be specially cemented on the roofs. Corn and hay stacks suffer badly in this abnormal situation.
The whole of the north end of Mull consists of green even terraces with occasional gullies. The islands of Ulva and Gometra are similarly terraced flat cones with occasional gullies. The ground is porous and does not form basins for freshwater lochs; peat is absent. Bracken grows rampant here; indeed, Ulva is almost a museum piece for showing what luxuriant growth bracken can make in the Highlands. On the terraces, only the tips of the horns of Highland cattle can be seen above the fronds, but in the gullies the bracken tries to reach the same height as the plants on the terraces and may grow to a height of 12–15 feet. Trees of many kinds grow well in the sheltered parts of Mull on this soil from the volcanic rock. Just as trees were impossible on the tertiary basalt cliffs of Balmeanach and on Inchkenneth, they reach extraordinary luxuriance and beauty where the calcareous cretaceous sandstone appears again round the edge of Carsaig Bay on the south coast of Mull. This pocket will well repay a visit from the botanist and, I should imagine, from the entomologist. The cliffs to the west of Carsaig are by no means as impressive as at Gribun, but in their face there is to be seen a fine fossil tree fern first brought to the notice of geologists and naturalists by Dr. Macculloch in the early 19th century (Macculloch, 1824). Delicately coloured crystals are also to be found in these cliffs of the south coast.
The south-east end of Mull is dominated by bosses of gabbro called Sgurr Bhuidhe and Creach Bheinn (2,352 and 2,344 feet). From them we may look down on the north side to the long, bare, impressive valley of Glen More and on the south to the tree-lined waters of Loch Uisge and Loch Spelve. The southern peninsula of Laggan, formed by Loch Buie and Loch Spelve and almost made an island by Loch Uisge, reaches nowhere to more than 1,250 feet, but it is extremely rough and rocky, with plenty of scrub birch. Few people have walked through that ground which for many years now has been kept as a small and very private deer forest of 5,000 acres.
The islands of Muck and Canna are both of tertiary basalt on an erosion platform at tide level of lava that looks like clinker. Their soil is so good and their position in the Atlantic so favoured that these islands can grow what are probably the earliest potatoes in Scotland, i.e., May 31. The sheep of these islands do extremely well and come to the mainland
