The projecting mass of land between Tramore Bay and the mouth of the River Suir consists of Old Red Sandstone, and the cliffs are mostly high, bold, and precipitous. The valleys which descend to the sea are more or less filled with Boulder-clay and other drift materials, testifying to their pre-Glacial oxcavation. The geological history of these valleys and of the large shallow lagoon lying inside the long spit of sand dunes which nearly cuts off the head of Tramore Bay deserves a separate article, and we will therefore here commence with the description of the eastern shore of this bay stretching from Summerville to Brownstown Head. Messrs. Wright & Muff in their paper on the pre-Glacial shore-line of the South of Ireland made no reference to this portion of the Waterford coast.

The cliff below Summerville House is composed of the usual type of Boulder-clay of the district, but devoid of any large boulders; it is capped by 4–8 inches of whitish to yellow marl without any stones; above this comes 1–2 feet of wind-blown sand immediately beneath the thin soil. The Boulder-clay here is only about 6 feet thick, and the total height of the cliffs is only 8–12 feet. The line of these drift-formed cliffs recedes inland behind the large triangular area of grass-grown hummocky land which projects seawards at Bass Point; this area represents a comparatively recent accumulation of sand which has been built outwards for some 200 yards from the base of the cliffs so as to narrow the channel of Rinnashark Harbour leading into the Back Strand lagoon.