DESORIPTION OF THE ISLE OF MAN xix 
extent also adjoins the Ayre on the south, and is still 
called Lough Cranstal, though it shows a sheet of water 
in winter only; and similar tracts of yet smaller extent 
are the Lagagh Moar in Andreas, in which are traces of 
ancient fortification, and Lough Pherick on the borders of 
Bride and Lezayre. 
The precise extent and situation of the former Curragh 
lakes is now somewhat uncertain, but three are shown 
in a map (very faulty and out of scale) of the sixteenth 
century ; and earlier in the Middle Ages we read of a lake at 
Myrosco, and three islands at least, ‘in bosco de Myrosco,’ in 
the thicket of Myrosco (on one of its islands was apparently 
a fort). The Manx Society’s editor queries ‘lacu’ for 
‘bosco, but any one who has seen the wetter Curragh even 
at the present day can well understand how drier land in 
the midst of it might be described as an island. The. 
Curragh was drained mainly in the seventeenth century. 
It is supposed that the slightly marked valley of the Lhen 
trench was the original course to the sea of the Sulby 
river, which has, in times geologically recent, been diverted 
by the dam of gravel piled up by the force of its own 
stream. 
II, THe CENTRAL HILL DISTRICT—-INLAND. 
To the south-west of the northern plain is the main mass 
of the isle, a range of hills mainly of schist,’ whose higher 
elevations occupy its centre, while its spurs fill the rest of 
the surface to the coast on either side. From Douglas to 
1 This hilly backbone of the island is very ancient. However altered by the 
addition and denudation of subsequent deposits, however at various periods 
elevated and depressed, now joined to the opposite hills by land, and now 
separated by water, moulded and carved by ice and flood, it has remained 
through countless ages to the present day the central feature of the hollow 
which is now the basin of the Irish Sea. . 
