The last detachments to quit the trenches moved off simultaneously all along the front at 1 r :45 P.M., without the enemy noticing their departure, and they were embarked successfully at " V " and " W " beaches according to schedule in spite of the heavy seas.
As these lakes shrank after the return of an arid climate, they left elevated beaches and deposits of various minerals, which mark their former extent.
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.
The beaches and lower lands are covered with a dense growth of tussock grass (Spartina arundinacea), 8 to 10 ft.
The island is of volcanic origin; the only signs of upheaval are raised limestone beaches in the extreme N.