Encyclopaedia Britannica, 11th Edition, "Ireland" to "Isabey, Jean Baptiste"

Chapter I: Part 1

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Transcriber's notes:

(1) Numbers following letters (without space) like C2 were originally
printed in subscript. Letter subscripts are preceded by an
underscore, like C_n.

(2) Characters following a carat (^) were printed in superscript.

(3) Side-notes were relocated to function as titles of their respective
paragraphs.

(4) Macrons and breves above letters and dots below letters were not
inserted.

(5) [root] stands for the root symbol; [alpha], [beta], etc. for greek
letters.

(6) The following typographical errors have been corrected:

ARTICLE IRELAND: "The Redistribution of Seats Act 1885 entirely
altered the parliamentary representation of Ireland. Twenty-two
small boroughs were disenfranchised." 'disenfranchised' amended
from 'disfranchized'.

ARTICLE IRELAND: "Catholics could not take longer leases than
thirty-one years at two-thirds of a rack rent; they were even
required to conform within six months of an inheritance accruing,
on pain of being ousted by the next Protestant heir." 'thirty'
amended from 'thiry'.

ARTICLE IRELAND: "It would be hard to name four other men who,
within the same period, used Shakespeare's language with equal
grace and force." 'four other' amended from 'other four'.

ARTICLE IRON AND STEEL: "This usefulness iron owes in part, indeed,
to its abundance, through which it has led us in the last few
thousands of years to adapt our ways to its properties; but still
in chief part first to the single qualities in which it excels,
such as its strength, its magnetism ..." Added 'properties'.

ENCYCLOPAEDIA BRITANNICA

A DICTIONARY OF ARTS, SCIENCES, LITERATURE
AND GENERAL INFORMATION

ELEVENTH EDITION

VOLUME XIV, SLICE VII

Ireland to Isabey, Jean Baptiste

ARTICLES IN THIS SLICE:

IRELAND IRONWOOD
IRELAND, CHURCH OF IRON-WOOD
IRENAEUS IRONY
IRENE IROQUOIS
IRETON, HENRY IRRAWADDY
IRIARTE Y OROPESA, TOMAS DE IRREDENTISTS
IRIDACEAE IRRIGATION
IRIDIUM IRULAS
IRIGA IRUN
IRIS (Greek mythology) IRVINE
IRIS (botany) IRVING, EDWARD
IRISH MOSS IRVING, SIR HENRY
IRKUTSK (government of Russia) IRVING, WASHINGTON
IRKUTSK (Russian town) IRVINGTON
IRMIN ISAAC (child of Abraham)
IRNERIUS ISAAC I.
IRON ISAAC II.
IRON AGE ISAAC OF ANTIOCH
IRON AND STEEL ISABELLA (queen of Castile)
IRON MASK ISABELLA II.
IRON MOUNTAIN ISABELLA (wife of Charles VI)
IRONSIDES ISABELLA OF HAINAUT
IRONTON ISABEY, JEAN BAPTISTE

IRELAND, an island lying west of Great Britain, and forming with it the United Kingdom of Great Britain and Ireland. It extends from 51 deg. 26' to 55 deg. 21' N., and from 5 deg. 25' to 10 deg. 30' W. It is encircled by the Atlantic Ocean, and on the east is separated from Great Britain by narrow shallow seas, towards the north by the North Channel, the width of which at the narrowest part between the Mull of Cantire (Scotland) and Torr Head is only 13(1/2) m.; in the centre by the Irish Sea, 130 m. in width, and in the south by St George's Channel, which has a width of 69 m. between Dublin and Holyhead (Wales) and of 47 m. at its southern extremity. The island has the form of an irregular rhomboid, the largest diagonal of which, from Torr Head in the north-east to Mizen Head in the south-west, measures 302 m. The greatest breadth due east and west is 174 m., from Dundrum Bay to Annagh Head, county Mayo; and the average breadth is about 110 m. The total area is 32,531 sq. m.

Ireland is divided territorially into four provinces and thirty-two counties:--(a) _Ulster_ (northern division): Counties Antrim, Armagh, Cavan, Donegal, Down, Fermanagh, Londonderry, Monaghan, Tyrone. (b) _Leinster_ (eastern midlands and south-east): Counties Carlow, Dublin, Kildare, Kilkenny, King's County, Longford, Louth, Meath, Queen's County, Westmeath, Wexford, Wicklow. (c) _Connaught_ (western midlands): Counties Galway, Leitrim, Mayo, Roscommon, Sligo. (d) _Munster_ (south-western division): Counties Clare, Cork, Kerry, Limerick, Tipperary, Waterford.

_Physical Geography._--Ireland stands on the edge of the European "continental shelf." Off the peninsula of Mullet (county Mayo) there are 100 fathoms of water within 25 m. of the coast which overlooks the Atlantic; eastward, northward and southward, in the narrow seas, this depth is never reached. The average height of the island is about 400 ft., but the distribution of height is by no means equal. The island has no spinal range or dominating mountain mass. Instead, a series of small, isolated clusters of mountains, reaching from the coast to an extreme distance of some 70 m. inland, almost surrounds a great central plain which seldom exceeds 250 ft. in elevation. A physical description of Ireland, therefore, falls naturally under three heads--the coasts, the mountain rim and the central plain.

Coasts.

The capital city and port of Dublin lies a little south of the central
point of the eastern coast, at the head of a bay which marks a sudden
change in the coastal formation. Southward from its northern horn, the
rocky headland of Howth, the coast is generally steep, occasionally
sheer, and the mountains of county Wicklow approach it closely.
Northward (the direction first to be followed) it is low, sandy and
fringed with shoals, for here is one point at which the central plain
extends to the coast. This condition obtains from 53 deg. 25' N. until
at 54 deg. N. the mountains close down again, and the narrow inlet or
fjord of Carlingford Lough separates the abrupt heights of the
Carlingford and Mourne Mountains. Then the low and sandy character is
resumed; the fine eastward sweep of Dundrum Bay is passed, the coast
turns north again, and a narrow channel gives entry to the
island-studded lagoon of Strangford Lough. Reaching county Antrim,
green wooded hills plunge directly into the sea; the deep Belfast
Lough strikes some 10 m. inland, and these conditions obtain nearly to
Fair Head, the north-eastern extremity of the island. Here the coast
turns westward, changing suddenly to sheer cliffs, where the basaltic
formation intrudes its strange regular columns, most finely developed
in the famous Giant's Causeway.

The low land surrounding the plain-track of the Bann intervenes
between this and the beginning of a coastal formation which is common
to the north-western and western coasts. From the oval indentation of
Lough Foyle a bluff coast trends north-westward to Malin Head, the
northernmost promontory of the island. Thence over the whole southward
stretch to Mizen Head in county Cork is found that physical appearance
of a cliff-bound coast fretted with deep fjord-like inlets and fringed
with many islands, which throughout the world is almost wholly
confined to western seaboards. Mountains impinge upon the sea almost
over the whole length, sometimes, as in Slieve League (county
Donegal), immediately facing it with huge cliffs. Eight dominant
inlets appear. Lough Foyle is divided from Lough Swilly by the
diamond-shaped peninsula of Inishowen. Following the coast southward,
Donegal Bay is divided from Galway Bay by the hammer-like projection
of county Mayo and Connemara, the square inlet of Clew Bay
intervening. At Galway Bay the mountain barrier is broken, where the
great central plain strikes down to the sea as it does on the east
coast north of Dublin. After the stern coast of county Clare there
follow the estuary of the great river Shannon, and then three large
inlets striking deep into the mountains of Kerry and Cork--Dingle Bay,
Kenmare river and Bantry Bay, separating the prongs of the forklike
south-western projection of the island. The whole of this coast is
wild and beautiful, and may be compared with the west coast of
Scotland and even that of Norway, though it has a strong individuality
distinct from either; and though for long little known to travellers,
it now possesses a number of small watering-places, and is in many
parts accessible by railway. The islands though numerous are not as in
Scotland and Norway a dominant feature of the coast, being generally
small and often mere clusters of reefs. Exceptions, however, are Tory
Island and North Aran off the Donegal coast, Achill and Clare off
Mayo, the South Arans guarding Galway Bay, the Blasquets and Valencia
off the Kerry coast. On many of these desolate rocks, which could have
afforded only the barest sustenance, there are remains of the
dwellings and churches of early religious settlers who sought solitude
here. The settlements on Inishmurray (Sligo), Aranmore in the South
Arans, and Scattery in the Shannon estuary, had a fame as retreats of
piety and learning far outside Ireland itself, and the significance of
a pilgrimage to their sites is not yet wholly forgotten among the
peasantry, while the preservation of their remains has come to be a
national trust.

The south coast strikes a mean between the east and the west. It is
lower than the west though still bold in many places; the inlets are
narrower and less deep, but more easily accessible, as appears from
the commercial importance of the harbours of Cork and Waterford.
Turning northward to the east of Waterford round Carnsore Point, the
lagoon-like harbour of Wexford is passed, and then a sweeping, almost
unbroken, line continues to Dublin Bay. But this coast, though
differing completely from the western, is not lacking in beauty, for,
like the Mournes in county Down, the mountains of Wicklow rise close
to the sea, and sometimes directly from it.

Mountains.

Every mountain group in Ireland forms an individual mass, isolated by
complex systems of valleys in all directions. They seldom exceed 3000
ft. in height, yet generally possess a certain dignity, whether from
their commanding position or their bold outline. Every variety of form
is seen, from steep flat-topped table-mountains as near Loughs Neagh
and Erne, to peaks such as those of the Twelve Pins or Bens of
Connemara. Unlike the Scottish Highlands no part of them was capable
of sheltering a whole native race in opposition to the advance of
civilization, though early customs, tradition and the common use of
the Erse language yet survive in some strength in the wilder parts of
the west. From the coasts there is almost everywhere easy access to
the interior through the mountains by valley roads; and though the
plain exists unbroken only in the midlands, its ramifications among
the hills are always easy to follow. Plain and lowland of an elevation
below 500 ft. occupy nearly four-fifths of the total area; and if the
sea were to submerge these, four distinct archipelagos would appear, a
northern, eastern, western and south-western. The principal groups,
with their highest points, are the Mournes (Slieve Donard, 2796 ft.)
and the Wicklow mountains (Lugnaquilla, 3039) on the east; the
Sperrins (Sawel, 2240) in the north; the Derryveagh group in the
north-west (Errigal, 2466); the many groups or short ranges of Sligo,
Mayo and Galway (reaching 1695 ft. in the Twelve Pins of Connemara);
in the south-west those of Kerry and Cork, where in Carrantuohill or
Carntual (3414) the famous Macgillicuddy Reeks which beautify the
environs of Killarney include the highest point in the island; and
north-east from these, the Galtees of Tipperary (3018) and Slieve
Bloom, the farthest inland of the important groups. Nearer the south
coast are the Knockmealdown (2609) and Commeragh Mountains (2470) of
county Waterford.

Central plain.

It will be realized from the foregoing description that it is
impossible to draw accurate boundary lines to the great Irish plain,
yet it rightly carries the epithet central because it distinctly
divides the northern mountain groups from the southern. The plain is
closely correlated with the bogs which are the best known physical
characteristic of Ireland, but the centre of Ireland is not wholly
bog-land. Rather the bogs of the plain are intersected by strips of
low-lying firm ground, and the central plain consists of these bright
green expanses alternating with the brown of the bogs, of which the
best known and (with its offshoots) one of the most extensive is the
Bog of Allen in the eastern midlands. But the bogs are not confined to
the plain. They may be divided into black and red according to the
degree of moisture and the vegetable matter which formed them. The
black bogs are those of the plain and the deeper valleys, while the
red, firmer and less damp, occur on the mountains. The former supply
most of the peat, and some of the tree-trunks dug out of them have
been found so flexible from immersion that they might be twisted into
ropes. Owing to the quantity of tannin they contain, no harmful miasma
exhales from the Irish bogs.

Rivers.

The central plain and its offshoots are drained by rivers to all the
coasts, but chiefly eastward and westward, and the water-partings in
its midst are sometimes impossible to define. The main rivers,
however, have generally a mountain source, and according as they are
fed from bogs or springs may be differentiated as black and bright
streams. In this connexion the frequent use of the name Blackwater is
noticeable. The principal rivers are--from the Wicklow Mountains, the
Slaney, flowing S. to Wexford harbour, and the Liffey, flowing with a
tortuous course N. and E. to Dublin Bay; the Boyne, fed from the
central plain and discharging into Drogheda Bay; from the mountains of
county Down, the Lagan, to Belfast Lough, and the Bann, draining the
great Lough Neagh to the northern sea; the Foyle, a collection of
streams from the mountains of Tyrone and Donegal, flowing north to
Lough Foyle. On the west the rivers are generally short and
torrential, excepting the Erne, which drains the two beautiful loughs
of that name in county Fermanagh, and the Shannon, the chief river of
Ireland, which, rising in a mountain spring in county Cavan, follows a
bow-shaped course to the south and south-west, and draws off the major
part of the waters of the plain by tributaries from the east. In the
south, the Lee and the Blackwater intersect the mountains of Kerry and
Cork flowing east, and turn abruptly into estuaries opening south.
Lastly, rising in the Slieve Bloom or neighbouring mountains, the
Suir, Nore and Barrow follow widely divergent courses to the south to
unite in Waterford harbour.

Lakes

The lakes (called loughs--pronounced _lochs_) of Ireland are
innumerable, and (apart from their formation) are almost all contained
in two great regions, (1) The central plain by its nature abounds in
loughs--dark, peat-stained pools with low shores. The principal of
these lie in county Westmeath, such as Loughs Ennel, Owel and
Derravaragh, famed for their trout-fishing in the May-fly season. (2)
The Shannon, itself forming several large loughs, as Allen, Ree and
Derg; and the Erne, whose course lies almost wholly through
loughs--Gowna, Oughter and the Loughs Erne, irregular of outline and
studded with islands--separate this region from the principal
lake-region of Ireland, coincident with the province of Connaught. In
the north lie Loughs Melvin, close above Donegal Bay, and Gill near
Sligo, Lough Gara, draining to the Shannon, and Lough Conn near
Ballina (county Mayo), and in the south, the great expanses of Loughs
Mask and Corrib, joined by a subterranean channel. To the west of
these last, the mountains of Connemara and, to a more marked degree,
the narrow plain of bog-land between them and Galway Bay, are sown
with small lakes, nearly every hollow of this wild district being
filled with water. Apart from these two regions the loughs of Ireland
are few but noteworthy. In the south-west the lakes of Killarney are
widely famed for their exquisite scenic setting; in the north-east
Lough Neagh has no such claim, but is the largest lake in the British
Isles, while in the south-east there are small loughs in some of the
picturesque glens of county Wicklow.

_Climate._--The climate of Ireland is more equable than that of Great Britain as regards both temperature and rainfall. No district in Ireland has a rainfall so heavy as that of large portions of the Highlands of Scotland, or so light as that of several large districts in the east of Great Britain. In January the mean temperature scarcely falls below 40 deg. F. in any part of Ireland, whereas over the larger part of the eastern slope of Great Britain it is some 3 deg. lower; and in July the extremes in Ireland are 59 deg. in the north and 62 deg. in Kilkenny. The range from north to south of Great Britain in the same month is some 10 deg., but the greater extent of latitude accounts only for a part of this difference, which is mainly occasioned by the physical configuration of the surface of Ireland in its relations to the prevailing moist W.S.W. winds. Ireland presents to these winds no unbroken mountain ridge running north and south, which would result in two climates as distinct as those of the east and west of Ross-shire; but it presents instead only a series of isolated groups, with the result that it is only a few limited districts which enjoy climates approaching in dryness the climates of the whole of the eastern side of Great Britain. (O. J. R. H.)

_Geology._--Ireland, rising from shallow seas on the margin of the
submarine plateau of western Europe, records in its structure the
successive changes that the continent itself has undergone. The first
broad view of the country shows us a basin-shaped island consisting of
a central limestone plain surrounded by mountains; but the diverse
modes of origin of these mountains, and the differences in their
trend, suggest at once that they represent successive epochs of
disturbance. The north-west highlands of Donegal and the Ox Mountains,
with their axes of folding running north-east and south-west, invite
comparison with the great chain of Leinster, but also with the
Grampians and the backbone of Scandinavia. The ranges from Kerry to
Waterford, on the other hand, truncated by the sea at either end, are
clearly parts of an east and west system, the continuation of which
may be looked for in South Wales and Belgium. The hills of the
north-east are mainly the crests of lava-plateaux, which carry the
mind towards Skye and the volcanic province of the Faeroe Islands. The
two most important points of contrast between the geology of Ireland
and that of England are, firstly, the great exposure of Carboniferous
rocks in Ireland, Mesozoic strata being almost absent; and, secondly,
the presence of volcanic rocks in place of the marine Eocene of
England.

The fact that no Cambrian strata have been established by
palaeontological evidence in the west of Ireland has made it equally
difficult to establish any pre-Cambrian system. The great difference
in character, however, between the Silurian strata at Pomeroy in
county Tyrone and the adjacent metamorphic series makes it highly
probable that the latter masses are truly Archean. They form an
interesting and bleak moorland between Cookstown and Omagh, extending
north-eastward into Slieve Gallion in county Londonderry, and consist
fundamentally of mica-schist and gneiss, affected by earth-pressures,
and invaded by granite near Lough Fee. The axis along which they have
been elevated runs north-east and south-west, and on either flank a
series of "green rocks" appears, consisting of altered amygdaloidal
andesitic lavas, intrusive dolerites, coarse gabbros and diorites, and
at Beagh-beg and Creggan in central Tyrone ancient rhyolitic tuffs.
Red and grey cherts, which have not so far yielded undoubted organic
remains occur in this series, and it has in consequence been compared
with the Arenig rocks of southern Scotland. The granite invades this
"green-rock" series at Slieve Gallion and elsewhere, but is itself
pre-Devonian. Even if the volcanic and intrusive basic rocks prove to
be Ordovician (Lower Silurian), which is very doubtful, the
metamorphic series of the core is clearly distinct, and appears to be
"fundamental" so far as Ireland is concerned.

The other metamorphic areas of the north present even greater
difficulties, owing to the absence of any overlying strata older than
the Old Red Sandstone. Their rocks have been variously held to be
Archean, Cambrian and Silurian, and their general trend has
undoubtedly been determined by post-Silurian earth-movements. Hence it
is useful to speak of them merely as "Dalradian," a convenient term
invented by Sir A. Geikie for the metamorphic series of the old
kingdom of Dalriada. They come out as mica-schists under the
Carboniferous sandstones of northern Antrim, and disappear southward
under the basaltic plateaux. The red gneisses near Torr Head probably
represent intrusive granite; and this small north-eastern exposure is
representative of the Dalradian series which covers so wide a field
from central Londonderry to the coast of Donegal. The oldest rocks in
this large area are a stratified series of mica-schists, limestones
and quartzites, with numerous intrusive sheets of diorite, the whole
having been metamorphosed by pressure, with frequent overfolding.
Extensive subsequent metamorphism has been produced by the invasion of
great masses of granite. Similar rocks come up along the Ox Mountain
axis, and occupy the wild west of Mayo and Connemara. The quartzites
here form bare white cones and ridges, notably in Errigal and Aghla
Mt. in county Donegal, and in the group of the Twelve Bens in county
Galway.

Following on these rocks of unknown but obviously high antiquity, we
find fossiliferous Ordovician (Lower Silurian) strata near Killary
harbour on the west, graduating upwards into a complete Gotlandian
(Upper Silurian) system. Massive conglomerates occur in these series,
which are unconformable on the Dalradian rocks of Connemara. In the
Wenlock beds of the west of the Dingle promontory there are
contemporaneous tuffs and lavas. Here the Ludlow strata are followed
by a thick series of barren beds (the Dingle Beds), which have been
variously claimed as Upper Silurian and Lower Devonian. No certain
representative of the Dingle Beds has been traced elsewhere throughout
the south of Ireland, where the Old Red Sandstone succeeds the
uptilted Silurian strata with striking unconformity. The Silurian
rocks were indeed greatly folded before the Old Red Sandstone was laid
down, the general trend of the folds being from south-west to
north-east. The best example of these folds is the axis of Leinster,
its core being occupied by granite which is now exposed continuously
for 70 m., forming a moorland from Dublin to New Ross. On either flank
the Silurian shales, slates and sandstones, which are very rarely
fossiliferous, rise with steep dips. They are often contorted, and
near the contact with the granite pass into mica-schists and
quartzites. The foothills and lowlands throughout southern Wicklow and
almost the whole of Wexford, and the corresponding country of western
Wicklow and eastern Kildare, are thus formed of Silurian beds, in
which numerous contemporaneous and also intrusive igneous rocks are
intercalated, striking like the chain N.E. and S.W. In south-eastern
Wexford, in northern Wicklow (from Ashford to Bray), and in the
promontory of Howth on Dublin Bay, an apparently earlier series of
green and red slates and quartzites forms an important feature. The
quartzites, like those of the Dalradian series, weather out in cones,
such as the two Sugarloaves south of Bray, or in knob-set ridges, such
as the crest of Howth or Carrick Mt. in county Wicklow. The radial or
fan-shaped markings known as _Oldhamia_ were first detected in this
series, but are now known from Cambrian beds in other countries; in
default of other satisfactory fossils, the series of Bray and Howth
has long been held to be Cambrian.

All across Ireland, from the Ballyhoura Hills on the Cork border to
the southern shore of Belfast Lough, slaty and sandy Silurian beds
appear in the axes of the anticlinal folds, surrounded by Old Red
Sandstone scarps or Carboniferous Limestone lowlands. These Silurian
areas give rise to hummocky regions, where small hills abound, without
much relation to the trend of the axis of elevation. The most
important area appears north of the town of Longford, and extends
thence to the coast of Down. In Slieve Glah it reaches a height of
1057 ft. above the sea. Granite is exposed along its axis from near
Newry to Slieve Croob, and again appears at Crossdoney in county
Cavan. These occurrences of granite, with that of Leinster, in
connexion with the folding of the Silurian strata, make it highly
probable that many of the granites of the Dalradian areas, which have
a similar trend and which have invaded the schists so intimately as to
form with them a composite gneiss, date also from a post-Silurian
epoch of earth-movement. Certain western and northern granites are
however older, since granite boulders occur in Silurian conglomerates
derived from the Dalradian complex.

This group of N.E. and S.W. ridges and hollows, so conspicuous in the
present conformation of Donegal, Sligo and Mayo, in the axis of Newry,
and in the yet bolder Leinster Chain, was impressed upon the Irish
region at the close of Silurian times, and is clearly a part of the
"Caledonian" system of folds, which gave to Europe the guiding lines
of the Scottish Highlands and of Scandinavia.

On the land-surface thus formed the Devonian lakes gathered, while the
rivers poured into them enormous deposits of sand and conglomerate. A
large exposure of this Old Red Sandstone stretches from Enniskillen
to the Silurian beds at Pomeroy, and some contemporaneous andesites
are included, reminding us of the volcanic activity at the same epoch
in Scotland. The numerous "felstone" dikes, often lamprophyric,
occurring in the north and west of Ireland, are probably also of
Devonian age. The conglomerates appear at intervals through the
limestone covering of central Ireland, and usually weather out as
conspicuous scarps or "hog's-backs." The Slieve Bloom Mountains are
thus formed of a dome of Old Red Sandstone folded on a core of
unconformable Silurian strata; while in several cases the domes are
worn through, leaving rings of Old Red Sandstone hills, scarping
inwards towards broad exposures of Silurian shales. The Old Red
Sandstone is most fully manifest in the rocky or heather-clad ridges
that run from the west of Kerry to central Waterford, rising to 3414
ft. in Carrantuohill in Macgillicuddy's Reeks, and 3015 ft. in
Galtymore. In the Dingle Promontory the conglomerates of this period
rest with striking unconformity on the Dingle Beds and Upper Silurian
series. Here there may be a local break between Lower and Upper
Devonian strata. The highest beds of Old Red Sandstone type pass up
conformably in the south of Ireland into the Lower Carboniferous,
through the "Yellow Sandstone Series" and the "Coomhola Grits" above
it. The Yellow Sandstone contains _Archanodon_, the oldest known
fresh-water mollusc, and plant-remains; the Coomhola Grits are marine,
and are sometimes regarded as Carboniferous, sometimes as uppermost
Devonian.

In the south, the Carboniferous deposits open with the Carboniferous
Slate, in the base of which the Coomhola Grits occur. Its lower part
represents the Lower Carboniferous Shales and Sandstones of the
central and northern areas, while its upper part corresponds with a
portion of the Carboniferous Limestone. The Carboniferous Limestone,
laid down in a sea which covered nearly the whole Irish area, appears
in the synclinal folds at Cork city and Kenmare, and is the prevalent
rock from the north side of the Knockmealdown Mountains to Enniskillen
and Donegal Bay. On the east it spreads to Drogheda and Dublin, and on
the west to the heart of Mayo and of Clare. Loughs Mask and Corrib are
thus bounded on the west by rugged Silurian and Dalradian highlands,
and on the east appear as mere water-filled hollows in the great
limestone plain.

The Lower Carboniferous Sandstones are conspicuous in the region from
Milltown near Inver Bay in southern Donegal to Ballycastle in county
Antrim. In the latter place they contain workable coal-seams. The
Carboniferous Limestone often contains black flint (chert), and at
some horizons conglomerates occur, the pebbles being derived from the
unconformable ridges of the "Caledonian" land. A black and often shaly
type called "calp" contains much clay derived from the same
land-surface. While the limestone has been mainly worn down to a
lowland, it forms fine scarps and table-lands in county Sligo and
other western regions. Subterranean rivers and water-worn caves
provide a special type of scenery below the surface. Contemporaneous
volcanic action is recorded by tuffs and lavas south-east of Limerick
and north of Philipstown. The beds above the limestone are shales and
sandstones, sometimes reaching the true Coal-Measures, but rarely
younger than the English Millstone Grit. They are well seen in the
high ground about Lough Allen, where the Shannon rises on them, round
the Castlecomer and Killenaule coalfields, and in a broad area from
the north of Clare to Killarney. Some coals occur in the Millstone
Grit horizons. The Upper Coal-Measures, as a rule, have been lost by
denudation, much of which occurred before Triassic times. South of the
line between Galway and Dublin the coal is anthracitic, while north of
this line it is bituminous. The northern coalfields are the L.
Carboniferous one at Ballycastle, the high outliers of Millstone Grit
and Coal-Measures round Lough Allen, and the Dungannon and Coalisland
field in county Tyrone. The last named is in part concealed by
Triassic strata. The only important occurrences of coal in the south
are in eastern Tipperary, near Killenaule, and in the Leinster
coalfield (counties Kilkenny and Carlow and Queen's County), where
there is a high synclinal field, including Lower and Middle
Coal-Measures, and resembling in structure the Forest of Dean area in
England.

The "Hercynian" earth-movements, which so profoundly affected
north-west and north-central Europe at the close of Carboniferous
times, gave rise to a series of east and west folds in the Irish
region. The Upper Carboniferous beds were thus lifted within easy
reach of denuding forces, while the Old Red Sandstone, and the
underlying "Caledonian" land-surface, were brought up from below in
the cores of domes and anticlines. In the south, even the
Carboniferous Limestone has been so far removed that it is found only
in the floors of the synclinals. The effect of the structure of these
folds on the courses of rivers in the south of Ireland is discussed in
the paragraphs dealing with the geology of county Cork. The present
central plain itself may be regarded as a vast shallow synclinal,
including a multitude of smaller folds. The earth-wrinkles of this
epoch were turned into a north-easterly direction by the pre-existing
Leinster Chain, and the trend of the anticlinal from Limerick to the
Slieve Bloom Mountains, and that of the synclinal of Millstone Grit
and Coal-Measures from Cashel through the Leinster coalfield, bear
witness to the resistance of this granite mass. The Triassic beds rest
on the various Carboniferous series in turn, indicating, as in
England, the amount of denudation that followed on the uplift of the
Hercynian land. Little encouragement can therefore be given in Ireland
to the popular belief in vast hidden coalfields.

The Permian sea has left traces at Holywood on Belfast Lough and near
Stewartstown in county Tyrone. Certain conglomeratic beds on which
Armagh is built are also believed to be of Permian age. The Triassic
sandstones and marls, with marine Rhaetic beds above, are preserved
mainly round the basaltic plateaus of the north-east, and extend for
some distance into county Down. An elongated outlier south of
Carrickmacross indicates their former presence over a much wider area.
Rock-salt occurs in these beds north of Carrickfergus.

The Jurassic system is represented in Ireland by the Lower Lias alone,
and it is probable that no marine beds higher than the Upper Lias were
deposited during this period. From Permian times onward, in fact, the
Irish area lay on the western margin of the seas that played so large
a part in determining the geology of Europe. The Lower Lias appears at
intervals under the scarp of the basaltic plateaus, and contributes,
as in Dorsetshire and Devonshire, to the formation of landslips along
the coast. The alteration of the fossiliferous Lias by dolerite at
Portrush into a flinty rock that looked like basalt served at one time
as a prop for the "Neptunist" theory of the origin of igneous rocks.
Denudation, consequent on the renewed uplift of the country, affected
the Jurassic beds until the middle of Cretaceous times. The sea then
returned, in the north-east at any rate, and the first Cretaceous
deposits indicate the nearness of a shore-line. Dark "green-sands,"
very rich in glauconite, are followed by yellow sandstones with some
flint. These two stages represent the Upper Greensand, or the sandy
type of the English Gault. Further sands represent the Cenomanian. The
Turonian is also sandy, but in most areas was not deposited, or has
been denuded away during a local uplift that preceded Senonian times.
The Senonian limestone itself, which rests in the extreme north on
Trias or even on the schists, is often conglomeratic and glauconitic
at the base, the pebbles being worn from the old metamorphic series.
The term "Hibernian Greensand" was used by Tate for all the beds below
the Senonian; the quarrymen know the conglomeratic Senonian as
"Mulatto-stone." The Senonian chalk, or "White Limestone," is hard,
with numerous bands of flint, and suffered from denudation in early
Eocene times. Probably its original thickness was not more than 150
ft., while now only from 40 to 100 ft. remain. This chalk appears to
underlie nearly the whole basaltic plateaus, appearing as a fringe
round them, and also in an inlier at Templepatrick. The western limit
was probably found in the edge of the old continental land in Donegal.
Chalk flints occur frequently in the surface-deposits of the south of
Ireland, associated with rocks brought from the north during the
glacial epoch, and probably also of northern origin. It is just
possible, however, that here and there the Cretaceous sea that spread
over Devonshire may have penetrated the Irish area.

After the Irish chalk had been worn into rolling downs, on which
flint-gravels gathered, the great epoch of volcanic activity opened,
which was destined to change the character of the whole north-west
European area. The critical time had arrived when the sea was to be
driven away eastward, while the immense ridges due to the "Alpine"
movements were about to emerge as the backbones of new continental
lands. Fissure after fissure, running with remarkable constancy N.W.
and S.E., broke through the region now occupied by the British Isles,
and basalt was pressed up along these cracks, forming thousands of
dikes, from the coast of Down to the Dalradian ridges of Donegal. One
of these on the north side of Lough Erne is 15 m. long. The more
deep-seated type of these rocks is seen in the olivine-gabbro mass of
Carlingford Mountain; but most of the igneous region became covered
with sheets of basaltic lava, which filled up the hollows of the
downs, baked the gravels into a layer of red flints, and built up,
pile upon pile, the great plateaus of the north. There was little
explosive action, and few of the volcanic vents can now be traced.
After a time, a quiet interval allowed of the formation of lakes, in
which red iron-ores were laid down. The plant-remains associated with
these beds form the only clue to the post-Cretaceous period in which
the volcanic epoch opened, and they have been placed by Mr Starkie
Gardner in recent years as early Eocene. During this time of
comparative rest, rhyolites were extruded locally in county Antrim;
and there is very strong evidence that the granite of the Mourne
Mountains, and that which cuts the Carlingford gabbro, were added at
the same time to the crust. The basalt again broke out, through dikes
that cut even the Mourne granite, and some of the best-known columnar
masses of lava overlie the red deposits of iron-ore and mark this
second basaltic epoch. The volcanic plateaus clearly at one time
extended far west and south of their present limits, and the
denudation of the lava-flows has allowed a large area of Mesozoic
strata also to disappear.

Volcanic activity may have extended into Miocene times; but the only
fossiliferous relics of Cainozoic periods later than the Eocene are
the pale clays and silicified lignites on the south shore of Lough
Neagh, and the shelly gravels of pre-glacial age in county Wexford.
Both these deposits may be Pliocene. Probably before this period the
movements of subsidence had set in which faulted the basalt plateaus,
lowered them to form the basin of Lough Neagh, and broke up the
continuity of the volcanic land of the North Atlantic area. As the
Atlantic spread into the valleys on the west of Ireland, forming the
well-known marine inlets, Europe grew, under the influence of the
"Alpine" movements, upon the east; and Ireland was caught in, as it
were, on the western edge of the new continent. It seems likely that
it was separated from the British region shortly before the glacial
epoch, and that some of the ice which then abutted on the country
travelled across shallow seas. The glacial deposits profoundly
modified the surface of the country, whether they resulted from the
melting of the ice-sheets of the time of maximum glaciation, or from
the movements of local glaciers. Boulder-clays and sands, and gravels
rearranged by water, occur throughout the lowlands; while the eskers
or "green hills," characteristic grass-covered ridges of gravel, rise
from the great plain, or run athwart valleys and over hill-sides,
marking the courses of sub-glacial streams. When the superficial
deposits are removed, the underlying rocks are found to be scored and
smoothed by ice-action, and whole mountain-sides in the south and west
have been similarly moulded during the Glacial epoch. In numerous
cases, lakelets have gathered under rocky cirques behind the terminal
moraines of the last surviving glaciers.

There is no doubt that at this epoch various movements of elevation
and subsidence affected the north-west of Europe, and modern Ireland
may have had extensions into warmer regions on the west and south,
while the area now left to us was almost buried under ice. In
post-Glacial times, a subsidence admitted the sea into the Lagan
valley and across the eastern shore in several places; but elevation,
in the days of early human occupation, brought these last marine
deposits to light, and raised the beaches and shore-terraces some 10
to 20 ft. along the coast. At Larne, Greenore and in the neck between
Howth and Dublin, these raised beaches remain conspicuous. To sum up,
then, while the main structural features of Ireland were impressed
upon her before the opening of the Mesozoic era, her present outline
and superficial contours date from an epoch of climatic and
geographical change which falls within the human period.

See maps and explanatory memoirs of the _Geological Survey of
Ireland_ (Dublin); G. Wilkinson, _Practical Geology and Ancient
Architecture of Ireland_ (London, 1845); R. Kane, _Industrial
Resources of Ireland_ (2nd ed., Dublin, 1845); G. H. Kinahan, _Manual
of the Geology of Ireland_ (London, 1878); E. Hull, _Physical Geology
and Geography of Ireland_ (2nd ed., London, 1891); G. H. Kinahan,
_Economic Geology of Ireland_ (Dublin, 1889); A. McHenry and W. W.
Watts, _Guide to the Collection of Rocks and Fossils, Geol. Survey of
Ireland_ (2nd ed., Dublin, 1898). (G. A. J. C.)

ECONOMICS AND ADMINISTRATION

_Population._--Various computations are in existence of the population of Ireland prior to 1821, in which year the first government census was taken. According to Sir William Petty the number of inhabitants in 1672 was 1,320,000. About a century later the tax-collectors estimated the population at a little over 2,500,000, and in 1791 the same officials calculated that the number had risen to over 4,200,000. The census commissioners returned the population in 1821 as 6,801,827, in 1831 as 7,767,401, and in 1841 as 8,196,597. It is undoubted that a great increase of population set in towards the close of the 18th century and continued during the first 40 years or so of the 19th. This increase was due to a variety of causes--the improvement in the political condition of the country, the creation of leaseholds after the abolition of the 40s. franchise, the productiveness and easy cultivation of the potato, the high prices during the war with France, and probably not least to the natural prolificness of the Irish people. But the census returns of 1851 showed a remarkable alteration--a decrease during the previous decade of over 1,500,000--and since that date, as the following table shows, the continuous decrease in the number of its inhabitants has been the striking feature in the vital statistics of Ireland.

_Decrease per cent. of Population 1841-1901._

+----------+----------+----------+----------+----------+----------+----------+
| |1841-1851.|1851-1861.|1861-1871.|1871-1881.|1881-1891.|1891-1901.|
+----------+----------+----------+----------+----------+----------+----------+
| Leinster | 15.25 | 12.86 | 8.11 | 4.49 | 6.8 | 3.5 |
| Munster | 22.47 | 18.53 | 7.93 | 4.98 | 11.8 | 8.4 |
| Ulster | 15.69 | 4.85 | 4.23 | 5.11 | 7.07 | 2.4 |
| Connaught| 28.81 | 9.59 | 7.33 | 3.43 | 12.4 | 9.7 |
+----------+----------+----------+----------+----------+----------+----------+
| Ireland | 19.85 | 11.50 | 6.67 | 4.69 | 9.08 | 5.3 |
+----------+----------+----------+----------+----------+----------+----------+

The cause of the continuous though varying decrease which these figures reveal has been emigration. This movement of population took its first great impulse from the famine of 1846 and has continued ever since. When that disaster fell upon the country it found a teeming population fiercely competing for a very narrow margin of subsistence; and so widespread and devastating were its effects that between 1847 and 1852 over 1,200,000 of the Irish people emigrated to other lands. More than 1,000,000 of these went to the United States of America, and to that country the main stream has ever since been directed. Between 1851 and 1905 4,028,589 emigrants left Ireland--2,092,154 males and 1,936,435 females, the proportion of females to males being extraordinarily high as compared with the emigration statistics of other countries. Between these years the numbers fluctuated widely--1852 showing the highest total, 190,322 souls, and 1905 the lowest, 30,676 souls. Since 1892, however, the emigrants in any one year have never exceeded 50,000, probably because the process of exhaustion has been so long in operation. As Ireland is mainly an agricultural country the loss of population has been most marked in the rural districts. The urban population, indeed, has for some years shown a tendency to increase. Thus in 1841 the rural population was returned as 7,052,923 and the urban as 1,143,674, while the corresponding figures in 1901 were respectively 3,073,846 and 1,384,929. This is further borne out by the percentages given in the above table, from which it will be seen that the greatest proportional decrease of population has occurred in the two provinces of Munster and Connaught, which may be regarded as almost purely agricultural. That the United States remained the great centre of attraction for Irish emigrants is proved by the returns for 1905, which show that nearly 80% of the whole number for the year sailed for that country. Ireland does little to swell the rising tide of emigration that now flows from England and Scotland to British North America.

Turning now to the census figures of 1901, we find that the population had diminished as compared with 1891 by 245,975. During the decade only three counties, Dublin, Down and Antrim, showed any increase, the increase being due to the growth of certain urban areas. Of the total population of 4,458,775, 2,200,040 were males and 2,258,735 were females. The inhabitants of the rural districts (3,073,846) decreased during the decade by over 380,000; that of the urban districts, i.e. of all towns of not less than 2000 inhabitants (1,384,929) increased by over 140,000. This increase was mainly due to the growth of a few of the larger towns, notably of Belfast, the chief industrial centre of Ireland. Between 1891 and 1901 Belfast increased from 273,079 to 349,180; Dublin from 268,587 to 289,108; and Londonderry, another industrial centre in Ulster, from 33,200 to 39,873. On the other hand, towns like Cork (75,978), Waterford (26,743) and Limerick (38,085), remained almost stationary during the ten years, but the urban districts of Pembroke and of Rathmines and Rathgar, which are practically suburbs of Dublin, showed considerable increases.

From the returns of occupation in 1901, it appears that the indefinite
or non-productive class accounted for about 55% of the entire
population. The next largest class was the agricultural, which
numbered 876,062, a decrease of about 40,000 as compared with 1891.
The industrial class fell from 656,410 to 639,413, but this
represented a slight increase in the percentage of the population. The
professional class was 131,035, the domestic 219,418, and the
commercial had risen from 83,173 in 1891 to 97,889 in 1901. The
following table shows the number of births and deaths registered in
Ireland during the five years 1901-1905.

+------+---------+---------+
| | Births. | Deaths. |
+------+---------+---------+
| 1901 | 100,976 | 79,119 |
| 1902 | 101,863 | 77,676 |
| 1903 | 101,831 | 77,358 |
| 1904 | 103,811 | 79,513 |
| 1905 | 102,832 | 75,071 |
+------+---------+---------+

The number of illegitimate births is always very small in proportion
to the legitimate. In 1905 illegitimate births numbered 2710 or 2.6 of
the whole, a percentage which has been very constant for a number of
years.

_Railways._--The first act of parliament authorizing a railway in Ireland was passed in 1831. The railway was to run from Dublin to Kingstown, a distance of about 6 m., and was opened in 1834. In 1836 the Ulster railway to connect Belfast and Armagh, and the Dublin and Drogheda railway uniting these two towns were sanctioned. In the same year commissioners were nominated by the crown to inquire (_inter alia_) as to a general system for railways in Ireland, and as to the best mode of directing the development of the means of intercourse to the channels whereby the greatest advantage might be obtained by the smallest outlay. The commissioners presented a very valuable report in 1838, but its specific recommendations were never adopted by the government, though they ultimately proved of service to the directors of private enterprises. Railway development in Ireland progressed at first very slowly and by 1845 only some 65 m. of railway were open. During the next ten years, however, there was a considerable advance, and in 1855 the Irish railways extended to almost 1000 m. The total authorized capital of all Irish railways, exclusive of light railways, at the end of 1905 was L42,881,201, and the paid-up capital, including loans and debenture stock, amounted to L37,238,888. The total gross receipts from all sources of traffic in 1905 were L4,043,368, of which L2,104,108 was derived from passenger traffic and L1,798,520 from goods traffic. The total number of passengers carried (exclusive of season and periodical ticket-holders) was 27,950,150. Under the various acts passed to facilitate the construction of light railways in backward districts some 15 lines have been built, principally in the western part of the island from Donegal to Kerry. These railways are worked by existing companies.

The following table shows the principal Irish railways, their mileage
and the districts which they serve.

There is no lack of cross-channel services between Ireland and Great
Britain. Belfast is connected by daily sailings with Glasgow,
Ardrossan, Liverpool, Feetwood, Barrow and Heysham Harbour, Dublin
with Holyhead and Liverpool, Greenore (Co. Down) with Holyhead, Larne
(Co. Antrim) with Stranraer, Rosslare (Co. Wexford) with Fishguard and
Kingstown (Co. Dublin) with Holyhead.

_Navigable Waterways._--Ireland is intersected by a network of canals
and waterways, which if efficiently managed and developed would prove
of immense service to the country by affording a cheap means for the
carriage of goods, especially agricultural produce. Two canals--the
Grand and the Royal--connect Dublin with the Shannon; the former
leading from the south of Dublin to Shannon Harbour and thence on the
other side of that river to Ballinasloe, with numerous branches; the
latter from the north side of Dublin to Cloondera on the Shannon, with
a branch to Longford. The Barrow Navigation connects a branch of the
Grand canal with the tidal part of the river Barrow. In Ulster the
Bann navigation connects Coleraine, by means of Lough Neagh, with the
Lagan navigation which serves Belfast; and the Ulster canal connects
Lough Neagh with Lough Erne. The river Shannon is navigable for a
distance of 143 m. in a direct course and occupies almost a central
position between the east and west coasts.

_Agriculture._--Ireland possesses as a whole a soil which is naturally fertile and easily cultivated. Strong heavy clay soils, sandy and gravelly soils, are almost entirely absent; and the mixture of soil arising from the various stratifications and from the detritus carried down to the plains has created many districts of remarkable richness. The "Golden Vein" in Munster, which stretches from Cashel in Tipperary to near Limerick, probably forms the most fertile part of the country. The banks of the rivers Shannon, Suir, Nore, Barrow and Bann are lined with long stretches of flat lands capable of producing fine crops. In the districts of the Old and New Red Sandstone, which include the greater part of Cork and portions of Kerry, Waterford, Tyrone, Fermanagh, Monaghan, Mayo and Tipperary, the soil in the hollows is generally remarkably fertile. Even in the mountainous districts which are unsuitable for tillage there is often sufficient soil to yield, with the aid of the moist atmosphere, abundant pasturage of good quality. The excessive moisture in wet seasons in however hostile to cereal crops, especially in the southern and western districts, though improved drainage has done something to mitigate this evil, and might do a great deal more.

Irish political history has largely affected the condition of agriculture. Confiscations and settlements, prohibitive laws (such as those which ruined the woollen industry), penal enactments against the Roman Catholics, absenteeism, the creation for political purposes of 40s. freeholders, and other factors have combined to form a story which makes painful reading from whatever point of view, social or political, it be regarded. Happily, however, at the beginning of the 20th century Irish agriculture presented two new features which can be described without necessarily arousing any party question--the work of the Department of Agriculture and the spread of the principle of co-operation. Another outstanding feature has been the effect of the Land Purchase Acts in transferring the ownership of the land from the landlords to the tenants. Before dealing with these three features, some general statistics may be given bearing upon the condition of Irish agriculture.

_Number of Holdings._--Before 1846 the number of small holdings was
inordinately large. In 1841, for example, there were no less than
310,436 of between 1 and 5 acres in extent, and 252,799 of between 5
and 15 acres. This condition of affairs was due mainly to two
causes--to the 40s. franchise which prevailed between 1793 and 1829,
and after that date to the fierce competition for land by a rapidly
increasing population which had no other source of livelihood than
agriculture. But the potato famine and the repeal of the Corn Laws,
occurring almost simultaneously, caused an immediate and startling
diminution in the number of smaller holdings. In 1851 the number
between 1 and 5 acres in extent had fallen to 88,033 and the number
between 5 and 15 acres had fallen to 191,854. Simultaneously the
number between 15 and 30 acres had increased from 79,342 to 141,311,
and the number above 30 acres from 48,625 to 149,090.

Since 1851 these tendencies have not been so marked. Thus in 1905 the
number of holdings between 1 and 5 acres was 62,126, the number
between 5 and 15 acres 154,560, the number between 15 and 30 acres
134,370 and the number above 30 acres 164,747. Generally speaking,
however, it will be seen from the figures that since the middle of the
19th century holdings between 1 and 30 acres have decreased and
holdings over 30 acres have increased. Of the total holdings under 30
acres considerably more than one-third are in Ulster, and of the
holdings over 30 acres more than one-third are in Munster. The number
of holdings of over 500 acres is only 1526, of which 475 are in
Connaught. A considerable proportion, however, of these larger
holdings, especially in Connaught, consist of more or less waste land,
which at the best can only be used for raising a few sheep.

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