sits, as the scarps are approached, are
greensands of "Selbornian" age, succeeded by Cenomanian, and locally by
Turonian, sands. The Senonian series is represented by the White
Limestone, a hardened chalk with flints, which is often glauconitic and
conglomeratic at the base. Denudation in earliest Eocene times has
produced flint gravels above the chalk, and an ancient stream deposit of
chalk pebbles occurs at Ballycastle. The volcanic fissures that allowed
of the upwelling of basalt are represented by numerous dykes, many
cutting the earlier lava-flows as well as all the beds below them. The
accumulations of lava gave rise to the plateaus which form almost the
whole interior of the county. In a quiet interval, the Lower Eocene
plant-beds of Glenarm and Ballypalady were formed in lakes, where
iron-ores also accumulated. Rhyolites were erupted locally near Tardree,
Ballymena and Glenarm. The later basalts are especially marked by
columnar jointing, which determines the famous structures of the Giant's
Causeway and the coast near Bengore Head. Volcanic necks may be
recognized at Carrick-a-rede, in the intrusive mass of dolerite at
Slemish, at Carnmoney near Belfast, and a few other points. Fair Head is
formed of intrusive dolerite, presenting a superb columnar seaward face.
Faulting, probably in Pliocene times, lowered the basaltic plateaus to
form the basin of Lough Neagh, leaving the eastern scarp at heights
ranging up to 1800 ft. The glens of Antrim are deep notches cut by
seaward-running streams through the basalt scarp, their floors being
formed of Triassic or older rocks. Unlike most Irish counties, Antrim
owes its principal features to rocks of Mesozoic and Cainozoic age. At
Cushendun, however, a coarse conglomerate is believed to be Devonian,
while Lower Carboniferous Sandstones, with several coal-seams, form a
small productive basin at Ballycastle. The dolerite of Fair Head sends
off sheets along the bedding-planes of these carboniferous strata.
"Dalradian" schists and gneisses, with some dark limestones, come out in
the north-east of the county, forming a moorland-region between
Cushendun and Ballycastle. The dome of Knocklayd, capped by an outlier
of chalk and basalt, consists mostly of this far more ancient series.
Glacial gravels are well seen near Antrim town, and as drumlins between
Ballymena and Ballycastle. The drift-phenomena connected with the flow
of ice from Scotland are of special interest. Recently ele