Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/16

 4 the Banc de la Chole, extending in a WSW direction about the same length, and having only two fathoms water on it at low tides.

On the other side of Alderney to the north-west, is the passage of the Singe, which, although narrow, contains water for ships of great burthen. It is formed by the shores of Alderney and the little island Burhou, and like the other passage, is subject to a short and turbulent sea.

The Island of Alderney shelves to the NE, but it is also intersected by deep vallies. Its length is about three miles and a half, and its greatest breadth one and a half.

The whole of the southern and western part, from La Pendante to La Clanque, is bounded by cliffs from one hundred to two hundred feet in height, presenting various picturesque and striking scenes. The northern and eastern sides consist of low cliffs, alternating with small bays and flat shores.

This part of the island is formed of a reddish grit, and the western side of porphyry; in which respects Alderney differs from the others of the group; which do not contain either of those rocks, at least, in large masses.

The boundary of this grit to the south-west, may be determined by a line drawn from l'Etat to Braie, or nearly. It is an aggregate formed from a detritus of granite, regularly varying in its texture and colour. At the NE part of the island it is a red coarse-grained grit; but it becomes gradually whiter, and of a finer texture, towards the west, till it ceases; resembling there, the finest sandstone. It is stratified through its whole extent, in parallel and equal strata, of about a foot in thickness. These strata are straight and continuous wherever I have observed them, and are almost every where inclined in an angle of 45°, dipping towards the east. Here and there, are some strata of a more horizontal tendency. Their equality and the