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 in such good order that mainland buyers are hesitant to buy the lambs because they know they have nothing so good to offer them to keep them growing. The wealth of species of insects, molluscs and other invertebrates on these tertiary basalt islands is much greater than would be found on those of the Torridonian or gneiss formations, even though the basalt does not tend to allow lochans to form. The Glasgow University Expedition to Canna in 1936 published a full report of their extensive finds. Muck and Canna both offer the right kind of cliffs for sea birds, and Canna is also a breeding station for the Manx shearwater.
The island of Eigg (Plate 5) is a big shearwater station, the birds nesting well up towards the Sgurr, 1,280 feet. The Sgurr is the most obvious physical feature of Eigg and by far the island’s most interesting natural phenomenon. It is a geological curiosity which has shed light on the geology of other areas far distant. The late Sir Archibald Geikie solved the riddle which Hugh Miller answered unknowingly at an earlier date. The Sgurr itself is of pitchstone, resting on a thin river bed of conglomerate which contains fossil pieces of driftwood from some far distant time. Beneath this is the tertiary basalt again. The pitchstone shows columnar jointing in places, a character which is still more strongly marked on Oidhsgeir, 18 miles away to WNW. This low islet of pitchstone is considered to be part of the same sheet as the Sgurr of Eigg. There is one other feature of Eigg deriving from its geology which should be mentioned here—the musical sands of Camus Sgiotag, a small bay on the north side of the island. These sands are of partially rounded quartz grains of similar size. If the sand is dry a shrill sound is heard as one walks over it.
To return for a moment to the few acres of Oidhsgeir, an islet which does not reach higher than 38 feet above sea level. Here on the top of the pitchstone columns which are 8 inches or so across the top are found the nests of kittiwakes in the season. There are also great numbers of common and arctic terns and eider ducks. Harvie-Brown, visiting the islet several times in the ’80’s and early ’90’s of last century found teal breeding and was convinced that the pintail duck had nested there also. This phenomenon of a small islet in the open sea gathering to it an immense number of living things for the purpose of their reproduction is one to which we shall return in a later chapter on the oceanic island. The deep-cut channels among the pitchstone columns are also a playground for the Atlantic seal. One channel on the south side runs up into a pool where a boat may lie in perfect safety. Many are the occasions when lobster fishers and venturers in small boats have been glad of the quiet pool of Oidhsgeir. What a strange feeling it is to be lying snug in such a place with the mighty ocean pounding but a few yards away and the spray flying over!
The island of Rum, with its three rock types of gabbro, Torridonian and granite, is for the most part a closed book to naturalists. We may hope this unfortunate period of its history is drawing to a close and that it may yet have a future as a priceless wild-life reserve. There are red deer and wild cats on Rum, there are otters round the shores and on the burns, and such species as badgers and roe deer could be introduced if introductions were thought desirable. Some of the finest kittiwake cliffs in the kingdom are to be seen on Rum, and the Manx shearwater nests in holes high up the 2,600-foot hills. The golden eagle is there still, though the sea eagle disappeared during the second half of the 19th century. Given the chance, we may expect the chough to return to Rum.
Skye may be looked