THE MIOCENE AND PLIOCENE FORMATIONS.
THE Eocene strata of England taken as a whole may be looked upon as estuarine beds. At the base,
the Woolwich and Reading beds, and also the upper parts of the series in the Isle of Wight and
Hampshire, consist of strata deposited in brackish, salt, and fresh water, at or near the mouth
of a great river, and the abundance of plants and terrestrial remains in the London Clay, and
other marine divisions of the series, proves that they also were deposited near the mouths of
such rivers, say, as the Mississippi and Amazon. Both in their lower and upper divisions, these
strata in France and England contain a large terrestrial mammalian fauna, the genera of which
are so antique that they have no very close relation with those now living. Nevertheless, they
are remotely related to living genera, and some may even be the direct ancestors of living
species through Miocene and Pliocene intermediate forms. To give an idea of the antiquity of this
old fauna, it is safe to say that when they lived the Alps had scarcely any place as a principal
This book has little to do with palæonto1ogy, but I have already stated in a previous chapter, that
in Germany there are formations containing terrestrial (as distinguished from marine fossils),
with mixed Eocene and Miocene generic forms, and I lay a little
[Miocene Epoch. 353]
stress on these points, because, after we get through these doubtful and fragmentary
stratigraphical and zoological gradations, we at length emerge on a time generally recognised as
Miocene or Middle Tertiary, the larger part of the flora and fauna of which has the closest
analogy to those that now inhabit the earth, the flora, possibly, even in part, specifically, and
part of the fauna, certainly generically. Most of the modern types are represented in one part of
the world or another: Elephant, Rhinoceros, Hippopotamus, Horses, Deer, Oxen, Camels,
Giraffes, Monkeys, and various carnivora. Nor are fresh-water reptilia wanting, though they
are less distinctive, some of the modern representatives of these animals having held their
place through longer epochs of time.
I recapitulate these facts, because the circumstances, bearing as they do on the present physical
geography of our part of the world, are very distinct, and I shall soon have something more to
say about the later unions of England with the Continent, and migrations of life consequent
The Hempstead beds of the Isle of Wight partly connect the Eocene and Miocene epochs, in so far
that the plants of these strata (always an imperfect guide) are related to Miocene species. But
stratigraphically, the Hempstead beds are inseparable from the Eocene beds below, and their
fossils, those that lived in water, are almost without exception the same.
True Miocene strata are very poorly represented in England, as shown in Chapter XVI., in the
description of Bovey Tracey, and they play no important part in its physical geography. The
slopes which surrounded the old lake of Bovey Tracey were clothed with splendid pines of the
genus Sequoia (Wellingtonia), oaks,
cinamons, figs, dryandra, prickly vines, nyssa, and other plants, and on the lake water-lilies
expanded their leaves and flowers.
The present Europe, partly then a continent, was, in Miocene times, the theatre of wide-spread
volcanic eruptions in Central France, Germany, and that part of the British Islands now known
as the Inner Hebrides, and also in the north-east of Ireland. In that region they play a much
more important part in connection with the physical geography of our country than they do at
Bovey Tracey. In the land of Antrim, from thence through the Isles of Mull, Rum, Eigg, Cana,
Muck, and Skye, a vast broken belt of Miocene volcanic rocks forms great part of the Inner
Hebrides; and far beyond Britain, in the Faroe Islands, Iceland, Spitzbergen, and Franz Joseph
Land, the same volcanic series is found, fragments perhaps of one large continuous territory,
or, if not, at all events of a series of large islands, of which the Faroes make one of the
In Scotland these volcanic rocks consist chiefly of Basalts, Dolerites, Feistones, and
Amygdaloids, interbedded with agglomerates of lapilli, large blocks, and volcanic bombs, such as
are piled on the sides of almost all volcanoes, and which often go by the name of volcanic ashes.
These occur, associated with beds of clay or soil, and streaks of lignite. Some of the clays contain
leaves of plants. The late Professor Edward Forbes determined their age, and later observations
made by Professor Heer confirm his accttracy.1
1 For an elaborate memoir on these volcanic rocks, see Mr. Judd 'On the Ancient Volcanoes of the
Highlands, &c., 'Journal of the Geological Society,' 1874, vol. xxx., p. 220. The whole subject
of the growth and decay of these volcanoes is there treated of in a manner never before
[Volcanic Rocks. 355]
It is clear that the beds of lignite in the Western Isles, and the shales with leaves, indicate long
pauses here and there in the activity of many craters. Vegetation on a large scale had time to
flourish. After an unknown lapse of time, the vast inclined plateaux of lava, above which the
lofty craters rose, are still, in Antrim, from 600 to 900 feet thick, and more than 3,000 feet
in Mull. The denuded edges of the several lava-streams now form a wonderful series of terraces,
rising tier upon tier, like Titanic steps, high on the hills on both sides of the Sound of Mull, and
the splendid columnar basalt of Fingal's Cave, in Staffa, is known to all tourists among the Inner
Hebrides. The same terraced forms are prominent in Skye, and in many of the smaller islands.
But where are the craters from which these vast volcanic piles of lavas and ashes were ejected?
They are all gone and utterly wasted away, and only their deepseated roots remain to mark the
sites, above which mountains grew by accretion, as high as Etna, which is growing even now. It
is a remarkable circumstance, and worthy to be noted, that these deep-seated centres of
crystalline rocks are now apt to form some of the highest portions of the islands. They have been
bared by denudation, and their hardness helps to preserve them.
Long before these extreme denudations
took place, when the islands formed part of a widespreading territory, old
river-beds intersected it, running through an ancient land, formed of Laurentian,
Cambrian, and Silurian rocks, that spread far to the west, north, and east.
These rivers scooped out valleys in the Miocene lavas and tufas, which were again partly filled
by torrents of basalt and obsidian. In the case of the
[356 Miocene Denudations.]
Scuir of Eigg, the lava (obsidian 3, fig. 77) flowed over the valley gravel (2) and buried it.
Since then the waste has been so great, that the destruction of the older hills that bounded the
valley has literally exalted the valley and laid the hills low, for the obsidian was harder than
the walls of the valley, and has longer resisted destruction,
1. Old lavas, &c. 2. River valley scooped out by denudation.
3. Obsidian filling valley. 4. Present outline of the country
produced by later denudations.
and thus it happened that the Scuir of Eigg became one of the most striking peaks in the
Thus it also happens that in the old volcanic plateaux valleys a thousand feet deep have been
excavated, and the whole region has by denudation been changed into a line of fragmentary
islands, the high sea cliffs of which attest the greatness of the waste they have in time
During this time the greater contours of England remained the same, that is to say, the old
mountain lands of Devon, Wales, and Cumbria, though suffering from denudation, remained
mountainous still, and, together with the lower country, the whole was merely upheaved so far
that England was joined to the
1 See A. Geikie, 'Jour. Geol. Society,' xxvii., 'On Tertiary Volcanic Rocks.'
Continent, and over the land, mammalian races in late Miocene times migrated into our region,
their bones being now found buried at the bases both of the Coralline and Red Crag, but chiefly
in the latter. Probably they lived here in the earliest Pliocene times, as the relics of an older
Miocene fauna, and got intermixed with varieties and new species. These include Beaver, Deer,
Horse and Hipparion, Hyna, and a Felis; Bears, Pig, Tapir, Rhinoceros, Mastodon, and perhaps a
true Elephant,1 all belonging to genera with which we are quite familiar in the present world,
if we except the Hipparion and Mastodon, and these have close relations, the first with the horse
and the second with the elephant.
The Crag formations of England
in descending order consist of three divisions, Norwich Crag, Red Crag, and
Coralline Crag. The Red and Coralline Crags are rich in marine fossils, and
the Norwich Crag also contains a marine fauna, together with twenty-four
species of land and freshwater shells. According to Mr. Prestwich, the above-named
formations contain from 84 to 93 per cent. of living species. But though
very important in a stratigraphical point of view, when viewed in connection
with marine life, the Crag plays a very unimportant part in the physical
structure of England, occurring as they do only in a few small shelly patches
of insignificant thickness in Norfolk and
1 Castor veterior, Cervus dicranoceros, Equus plicidens (?), Felis pardoides, Hipparion, Hyena
antiqua, Mastodon arvernensis, Mastodon tapiroides (?), Elephas meridionalis (?) Rhinoceros
Schleirmacheri, Sus antiquus (?), Tapirus priscus, Ursus arvernensis, Megaceros Hibernicus
(?). See Prestwich, 'Journal Geol. Society,' 1871, vol. xxvii., p. 348. Mr. Prestwich considers
this fauna as probably of Pliocene age, that is to say, contemporaneous with the deposition of the
[358 Forest Bed.]
Suffolk. They are, in fact, often so far buried under superficial strata that they require to be
looked for, and the whole country being flat they do not at all affect the scenery, excepting in a
minor way in the coast cliffs. Physically they chiefly indicate a certain amount of submergence
and subsequent emergence in late times, before the epoch of the Forest bed, and that is all, for,
as already frequently insisted on, we are not to consider Great Britain as having always been an
island during and between the periods that I have already described. It is an accident that it is
now an island; and it has been islands many times, and an island more than once before, and in
many shapes. When I describe other periods, still later than the Crag, we shall be able to
understand a little more definitely the precise kind of changes that our land in latter days has
Younger than the Crag there are certain other minor deposits, portions of which are scattered
here and there throughout England. One of the most remarkable, the 'Forest bed,' lies
underneath the glacial deposits on the shore, at Cromer, in Norfolk. This minor formation has
been traced for some distance between high arid low water mark. It consists of dark sandy clay,
with plants, above which there is a band of coarse gravel, containing the remains of elephants,
&c., then bands of clay and gravel, with marine and freshwater shells and fragments of wood.
The plants noticed in the Forest bed are : Pinus sylvestris (Scotch fir), Abies excelsa (a Pine),
Taxus baccata (Yew), Prunus spinosa (Sloe), Menyanthes trifoliata (Buckbean), Quercus (Oak),
Alnus (Alder), Nymphœa alba (Water-lily), Nuphar lutea (Yellow Water-lily), Ceratophyllum demersum (Horn-wort), and Potamogeton
[Flora and Fauna. 359]
(Pondweed), together with fronds and rhizomes of ferns.
In the Forest bed and the overlying gravel the following land mammalia have been found: Elephas
antiquus (the ancestor of the African Elephant), E.
meridiomalis, Rhinoceros megarrhinus, R. Etruscus,
Hippopotamus major, Equus caballus (the common
horse), Machairodus (a tiger ?), Bison priscus (?), Bos
primigenius (Aurochs), Sus Arvernensis; four species of bears, Ursus Arvernensis, U.
Spelœus (Cave bear ?), U. Etruscus, U. arctos (White bear) ; six species of deer, Cervus
megaceros (often miscalled the Irish elk), C. elaphus (Red deer), C. Sedgwickii, C. Poligniacus, C. capreolus (Roedeer), Mygale moschata (Musk shrew), Sorex fodiens and S. remifer
(Shrews), Arvicola amphibia (Field-mouse), Castor Europœus (common beaver),
Trogontherium Cuvieri (a great Beaver), two species of whales, and fish.1 The whole speaks of a
past physical geography, at least during part of which, with a mild climate, our country seems
to have been joined to the Continent. It must, however, be confessed that this assemblage of
mammalia is not quite devoid of the appearance of being a little too miscellaneous, and several
authors have declared that some of the bones, having been picked up on the shore between high
and low water mark, may have been washed up from the neighbouring sea-bottom, and thus got
mixed with others of later geological date which really belong to the Forest bed. However this
may be I have given the list as it originally stood, with some slight corrections by Professor
Boyd Dawkins, and whichever theory be
The above list is taken from Mr. Prestwich 'On the Crag Beds
of Sufolk and Norfolk;' 'Quarter'y Journal of the Geological
Society,' vol. xxvii., p. 466.
[360 Forest Bed.]
true, it cannot fail to impress the reader as throwing light on some one of the ever-shifting
physical and biological phases that our country has undergone, each of which in its day seemed
as constant as that in the midst of which we live. The special episode of the Forest bed points to
this, that it exhibits a fragment of the vegetation and fauna of the last pre-glacial epoch, at a
time when England was united to the Continent, and when a flora and fauna, in part new,
migrated across the intervening plain into our area.