Part 3

{ {Chalk } { {Upper Greensand and Gault } Chalk at top {Cretaceous {Lower Greensand } Sandstones, Mud S{ {Weald Clay } and Clays below E{ {Hastings Sands } C{ O{ {Purbeck Beds } N{ {Portland Beds } D{ {Kimmeridge Clay } A{ {Corallian Beds } R{Jurassic {Oxford Clay and Kellaways Rock } Shales, Sandstones Y{ {Cornbrash } and Oolitic { {Forest Marble } Limestones { {Great Oolite with Stonesfield Slate} { {Inferior Oolite } { {Lias--Upper, Middle, and Lower } { { {Rhaetic } { {Keuper Marls } {Triassic {Keuper Sandstone } Red Sandstones and { {Upper Bunter Sandstone } Marls, Gypsum and { {Bunter Pebble Beds } Salt { {Lower Bunter Sandstone }

{ {Magnesian Limestone and Sandstone } Red Sandstones {Permian {Marl Slate } and Magnesian { {Lower Permian Sandstone } Limestone P{ R{ {Coal Measures } Sandstones, Shales I{Carboniferous {Millstone Grit } and Coals at top M{ {Mountain Limestone } Sandstones in A{ {Basal Carboniferous Rocks } middle Limestone R{ } and Shales below Y{ { {Upper } Devonian and old Red } Red Sandstones, {Devonian {Mid } Sandstone } Shales, Slates and { {Lower } } Limestones { { {Ludlow Beds } Sandstones, Shales {Silurian {Wenlock Beds } and Thin { {Llandovery Beds } Limestones { { {Caradoc Beds } Shales, Slates, {Ordovician {Llandeilo Beds }Sandstones and { {Arenig Beds } Thin Limestones { { {Tremadoc Slates } {Cambrian {Lingula Flags } Slates and { {Menevian Beds } Sandstones { {Harlech Grits and Llanberis Slates } { { {Sandstones, {Pre-Cambrian No definite classification yet made {Slates and {Volcanic Rocks

The North Devonian beds, which extend from the coast as far south as the latitude of Barnstaple, consist of slates, grits, and sandstones which, it is believed, judging from the organic remains in them, were formed in shallow water and near shore. Their lower strata, the Foreland grits, Lynton beds, and Hangman grits, contain some fossils and various kinds of coral. But the Middle beds, the Ilfracombe and Morte slates, are much richer in animal remains; of which perhaps the most remarkable are primitive palaeozoic fish, such as the very curious armoured _pteraspis_; while corals and bivalve shells are abundant and characteristic. The Upper Devonian is less fossiliferous, but contains some large trilobites, various marine shells, and some land-plants.

The South Devonian, which covers nearly all South Devon and a large part of Cornwall, is somewhat different in character, consisting chiefly of slates, with coralline limestones, varied by volcanic outcrops or elvans--a word said to be of Cornish origin, and meaning "white rock." To judge from its fossils, it was deposited in deeper water than the contemporary beds in the north of the county. The Lower and Middle beds are also far richer in animal remains; and the Middle Devonian of the south, which is the most typical of the series and includes the limestones of Plymouth and Torbay, is crowded with shells, trilobites, and corals. Among the shells, bivalves--such as _Stringocephalus_, which occurs only in the Devonian formations--spiral univalves, and corals are very abundant. There are also many crinoids, distinct from those of the carboniferous limestone, while perhaps the most characteristic form is the rare and curious _Caleola sandalina_, differing from all other corals in having an operculum. There are not many varieties of trilobite, but the large _Brontes flabellifer_ is not uncommon.

The Lower beds of this series contain fewer organic remains, although a good many fossils are found, including fragmentary remains of various fishes which have not yet been identified. The Upper Devonian is, on the whole, very poor in fossils.

Between the two Devonian areas, and occupying a large part of the centre of the county, are the carboniferous or coal-bearing measures, containing, however, not true coal but anthracite, which has more carbon in it than is found in ordinary coal; and these beds are perhaps more often known as Culm, from the Welsh _cwlwm_, a knot, in allusion to the fragmentary condition in which the mineral is frequently found. Anthracite, which elsewhere and especially in South Wales is a most valuable fuel, is here clayey and impure, and in thin seams. It is worked to a small extent, to be ground and made into a paint called Bideford Black. The Culm measures consist of grits, shales, and sandstones, with beds of chert and limestone containing fossil plants and other forms of marine life. Fish are few, only two species having been identified. The anthracite occurs in the middle Culm, and there are other remains of plants in both the middle and upper beds. The upper Culm is well seen on the coast near Clovelly and by the river Torridge, where it has been bent by volcanic upheaval into curious and beautiful curves. These measures, in general, are characterised by many outcrops of volcanic rock, some of which were probably contemporary, that is to say, they were poured out while the culm was in process of formation; while others are intrusive, or were forced up through the strata after these had been solidified into rock. These igneous rocks are found in great variety.

By far the most important and striking of these volcanic formations is the great granite mass of Dartmoor, one of the most prominent features of the county, measuring 225 square miles in extent, and constituting the largest granitic area in England. Granite is a volcanic rock, formed, it has been suggested, by fusion at a great depth and under great pressure, and consisting in the main of three minerals, quartz, felspar, and mica. That of Dartmoor is, on the whole, grey and coarse-grained, but it varies a good deal in colour, fineness, and composition. Its real origin is obscure. It has been assigned by various experts to various periods, and it has been called "the sphinx of Devon geology." There can, however, be no doubt about the great disturbance which has been caused in the county by upheaval and by the intrusion of melted rock, which has bent, broken, and twisted previously-existing formations in a most extraordinary manner, the results of which are well seen in the picturesque scenery of the Start, Prawle Point, and Bolt Head. Lundy, which is twelve miles from the nearest point of Devonshire mainland, is all granite, except for a small part of its south end, which is Millstone Grit.

A long interval of time appears to have followed the laying down of the Culm measures, during which so vast an amount of shattered rock was worn away that when the beds that come next in order--the New Red Sandstones--were formed, they were, in places, deposited directly upon the Devonian, the superincumbent carboniferous or Culm strata having entirely disappeared. The New Red Sandstones occur chiefly in the east of the county, where their lower beds fill up old creeks and valleys in the carboniferous system; and they extend northwards from the coast past Exeter as far as Holcombe Regis, forming broad bands on either side of the Exe, characterised by the high fertility of the overlying soil, and with one long spur traversing the heart of the county, past Crediton and Exbourne, with isolated patches round Hatherleigh, and with another and less extended prolongation a few miles west of Tiverton. The Lower New Red consists of clays, conglomerates, red breccias and sands, in which occur many outcrops of trap, the evidence, not only of numerous eruptions, but of eruptions extending over a long period of time. These beds contain no fossils, except in fragments of older rocks. The Middle New Red, in the form of thick beds of red marl and red and white limestones, well seen on the south coast, is covered in turn by the Upper New Red, with beds of pebbles, some of which are derived from the Devonian and even from the Silurian. In this formation, near Sidmouth, have been found the remains of two remarkable reptiles, the _Hyperodapedon_, a strange form allied to the existing tuatera lizard of New Zealand and in England only known elsewhere in the formations of Warwickshire, and the _Labyrinthodon_, so named from the intricate structure of its teeth, and also called _Cheirotherium_, from the hand-like impressions of its feet.

The Rhaetic beds are not well seen in Devonshire. They occur on the coast between Lyme Regis and the mouth of the Axe, and in the estuary of that river, but are much hidden by landslips of cretaceous formations from above. One layer, consisting of black shale, with bivalve shells such as _Cardium_ and _Pecten_, contains also a bone-bed, with remains of fish, such as _Acrodus_ and _Hybodus_. The former is represented by its blunt teeth, and the latter, which was a huge, shark-like creature, by its long and formidable-looking fin-spines.

The Lower Lias is exposed in a narrow strip of coast from the Devonshire border to the mouth of the Axe, and to a greater extent in the valley of the river above Axminster. It has been divided on the coast into four distinct zones, each characterised by its own particular species of ammonite.

The cretaceous formations occupy a much wider area, but they also are confined to the southern part of the county. The Greensands of the Blackdown and Haldon Hills have been divided by geologists into fifteen layers, varying in thickness from a few inches to as much as thirty-five feet, some with few fossils, and some very rich in animal remains. _Trigonia_ and _Inoceramus_ are found in almost all the zones: other forms less widely distributed are _Murex_ and _Turritella_. Chalk occurs on the south coast from the Dorset border to Sidmouth; and in isolated patches it extends inland as far as the Blackdown Hills, and also further west, in the Haldons. The Lower Chalk, well seen on the coast and to the west of Hinton, is made up of calcareous sandstones, with ammonites and pectens. The Middle beds, composed of white chalk with flints, the zone of _Terebratulina gracilis_, is exposed at Beer. The lower and harder layer is characterised by _Rhynconella_. The Upper Chalk also holds many flints, with echini; _Holaster_ in the lower, and _Micraster_ in the upper strata.

Last of all come the tertiary deposits, which, however, occupy only a small area in the south-east, chiefly in the valley of the Teign, from Kingsteignton to Bovey Tracy; and there are a few isolated patches, as for example near Bideford and at Plymouth. These beds consist of clays, some of them of much value, with flints from the chalk, and gravels and beds of sand derived from the wearing away of older rocks. The most interesting feature of this formation is the lignite of Bovey Tracy, on the eastern edge of Dartmoor. Lignite, otherwise known as brown coal, consists of the imperfectly fossilised remains of tropical or sub-tropical vegetation, such as the palm, cinnamon, and laurel, amongst which are found lumps of resin. By far the most abundant remains are those of a very large tree allied to the sequoia of California. It is very remarkable that in the Pleistocene clay above the lignite are found stems and twigs of Arctic birch and willow, suggestive of a far colder climate than prevailed in Tertiary times, when the trees that went to form the lignite were growing.

To the Pleistocene period also belong the gravels and alluvial deposits of some of the river valleys (those of the Exe and the Teign, for example), the blown sands of Braunton Burrows and elsewhere, the raised sea-beaches, the submerged forests, and the cave-deposits which are alluded to in other chapters.

7. Natural History.

It is generally believed by naturalists that the ancestors of most of our fauna and flora reached this country at a time when what we now call the British Isles formed part of the mainland of Europe, and when there was no intervening sea to bar the way.

Before this colonisation was complete, however--that is, before all the different kinds of European beasts and birds had made their way to the extreme western districts--communication with the continent was broken off. The land of the north-western districts of Europe sank. The sea flowed in, forming the German Ocean, the English Channel and the Irish Sea, and the influx of animal life was stopped.

This is the reason why there are more than twice as many kinds of land animals in Germany as there are in England, and nearly twice as many in England as there are in Ireland. This is the reason why there are no snakes in Ireland, and why the nightingale, on returning from the south, never crosses into the sister kingdom.

On islands that have long been separated from a continent it is found that forms of life tend to vary in the lapse of time, and that fresh species are developed. That it is not long, as geological periods go, since Great Britain became an island, is shown by the fact that we have no quadruped or reptile except the Irish weasel (_Mustela hibernica_), and, setting aside minor differences which some writers have magnified to the value of a species, only one bird, the red grouse, which is not also to be found in Europe. Very different is the case in Japan, which was separated from the mainland of Asia so long ago that new species have had time to develope; and the islands of that country contain many kinds of beasts and birds which are unknown on the adjacent continent.

Some of the animals which came from Europe into Britain have died out, either because the climate changed and so cut off their food supply, or because they were destroyed by the hunters of the Stone Age. The bones which have been found in Kent's Cavern at Torquay, and in other caverns, afford clear evidence that the mammoth, the lion, the bear, and the hyaena once roamed over the hills of Devonshire.

Although there are many more species of beasts and birds on the continent of Europe than there are in this country, both birds and beasts are numerically much more common here. Nothing strikes a naturalist more forcibly when travelling in France or Italy, for example, than the scarcity of wild life, and especially the fewness of the birds. It is true that we have fewer species, but we have many more individuals. To this, several causes have contributed. Englishmen do not, as is the custom in many European countries, shoot or trap for food small birds of every description. And game preserving--although it has been fatal to the larger birds of prey, such as kites, falcons, and buzzards, and keeps down other species, such as jays, magpies, and carrion crows--provides innumerable sanctuaries for great numbers of the smaller birds, which are safe from harm during the breeding season.

The natural features of Devonshire are so varied in character, including as they do large areas of wild and uncultivated and thinly-inhabited country, together with many well-wooded and sequestered valleys, and wide stretches of bog, salt-marsh, and sea-coast, that it is very rich in both animal and vegetable life. Its marine fauna and flora, in particular, are of very great interest, and are among the most remarkable in England.

Nearly all the native mammals of the British Isles are found or have been found in this county, from the "tall red deer" that has run wild on Exmoor from time immemorial, down to the pygmy shrew, the smallest but one of European quadrupeds, and weighing only one-tenth of an ounce, or about forty-three grains and a half.

Among the eight species of Devonshire bats is the very rare particoloured bat (_Vesperugo discolor_), of which the only example ever recorded in England was taken at Plymouth, having perhaps travelled there in the rigging of a ship. It is probably more than a hundred years since the last genuine wild-cat was seen in the county, but both the marten and the polecat still survive in secluded spots. Foxes are common, and there are still many badgers in some of the Dartmoor valleys, where the two species have been known to inhabit the same holt. Otters abound on all the principal streams, and are as regularly hunted as the red deer and the fox. Devonshire is, indeed, pre-eminent for its otter-hunting, and the Culmstock pack is believed to be the oldest in the island. Harvest mice and dormice, although widely distributed, are not numerous, and the original English black rat is now rare.

Among the many marine mammalia that have been recorded for the county are two kinds of seal, the sperm-whale, the common rorqual--of which specimens nearly 70 feet long have been brought into Plymouth--the rare bottle-nosed dolphin and the still rarer Risso's grampus. Bones of a whale called _Balaenoptera robustus_, which were once washed ashore in Torbay, are said to represent a species so rare that these and a few similar relics stranded in Sweden are the only remains of it that have ever been found.

Situated as Devonshire is, between the English and the Bristol Channels, and containing widely-different physical features, suited to the needs of species of very different habits, the list of its birds, including residents, migrants, occasional visitors, and stragglers from the Atlantic and even from America, is a very long one.

Among the larger land-birds which still hold their ground in the county are the raven and buzzard, both of which are to be seen on Exmoor and Dartmoor and on the coast, and the peregrine falcon, which has eyries on both the northern and southern seaboards. A few pairs of choughs still build in the northern cliffs; while such rare birds as Montagu's harrier--first identified as a British species in this county--the hoopoe, and the golden oriole still occasionally breed here, and might do so regularly were they left in peace. Several birds, such as the kite and the osprey, the latter of which now breeds nowhere in England, and the former only in one solitary spot, have long since left the county. Warblers as a family are less abundant than in some other parts of the British Isles. The nightingale is nowhere common, but it occurs every season near Ashburton and in the valley of the Teign. Owing to the mildness of the climate it is not at all an unusual thing for a few chiffchaffs and willow-warblers to spend the winter in sheltered valleys on the south coast, instead of migrating to Africa in the autumn. The ring-ouzel is a regular visitor to the open country of Dartmoor, while the dipper haunts many of its streams. Two birds which have greatly increased in numbers of late years are the jackdaw and the starling. It is thought that the former has done much towards exterminating the chough by destroying its eggs; and the latter, by taking possession of its holes, has in many places driven away the green woodpecker. Partridges and pheasants are numerous, but black-game, once abundant on Dartmoor, have become so scarce that they are at present protected the whole year round.

But by far the most abundant, and perhaps the most characteristic, of the birds of Devonshire are the sea-fowl, the water-fowl, and the waders, of which more than 140 different kinds have been recorded for the county. Not only are its sandy shores, its bays and estuaries and leys, haunted in autumn and winter by multitudes of northern immigrants--swans, geese, ducks and a great variety of wading-birds; but there are several spots along the south coast and a few on the north where sea-birds regularly breed; while the reed-beds of Slapton Ley provide sanctuary for great numbers of coots and for many wild-ducks and teal, together with some rarer species. Herons are common on the south coast and along the river estuaries, and there are heronries at Powderham and elsewhere. A great black-headed gull (_Larus ichthyaetus_) shot on the Exe in 1859, is the only one known to have been seen in the British Islands.

There is, however, nothing on the mainland of Devonshire to compare in ornithological interest with Lundy, which in the summer time is a bird-lover's paradise. Gannets, once very numerous, have now left the island, but cormorants, shags and gulls of various species here build their untidy nests. Here multitudes of guillemots and razorbills assemble in the spring and lay their great pear-shaped and boldly-marked eggs on the ledges of the cliffs; while even vaster hosts of puffins come back every year to take up their quarters in rabbit-burrows or in holes which they have dug for themselves in the turf. Here the raven, the buzzard, and the peregrine have fastnesses. Here, in chinks and crannies, storm-petrels breed; and here, when darkness falls, the startled listener may hear the weird, wailing cry of the night-wandering shearwaters.

The few reptiles and batrachians of Devonshire present no points of special interest. Vipers abound on Dartmoor, where they are commoner than grass-snakes. It is curious that, while the palmated newt is common throughout the county, the smooth newt and the triton are now comparatively rare.

The freshwater fish differ little from those found in the neighbouring counties; but there are fewer kinds in Devonshire than there are in the midlands or in the east of England. Trout abound in all the streams, and there are important salmon-fisheries on the Exe, the Dart, and other rivers. A sturgeon seven-and-a-half feet long was once taken in the Exe. Eels, which are hatched in the Atlantic, to the west and north of the British Islands, at a depth of 3000 feet or more, come up from the sea when they are two years old, and still very small, and ascend the rivers, especially Exe, in enormous numbers. When they are mature, which is not until they are several years old, they go down to the sea to spawn, and never return.