28 THE MAEINE AJAiJE OV GUERNSEY 



exception of some superficial pleistocene deposits no newer rocks are 

 found." Anstead notes that " the rocks are remarkably broken and 

 fissured by mineral veins, the enclosing rock and its veins being 

 of different degrees of hardness, and the equal action of the sea on 

 rocks of unequal hardness has produced those long lines of projecting 

 rocky islets, the many narrow inlets, and the intersecting floors 

 of rock between high and low water mark An extreme com- 

 plication of the vein system is beyond doubt the original cause of this 

 peculiarity." A more ideal habitat for the growth of seaweeds than 

 this coast with its wealth of boulders, nooks and crannies, overhanging 

 rocks and basins, deep or shallow, it would be diificult to imagine. 



Further information on the geology of the island is to be found in 

 contributions by Collinette and Derrick in their presidential addresses, 

 and byDunlop"On the vSuperficial Deposits of Guernsey" (Trans. 

 Guerns. Soc. Nat. Sci. iii. 1895-99). Accounts are given of the 

 successive periods of submergence and elevation of the island during 

 the Quaternary period : these changes of level were accompanied by 

 processes of denudation and subsequent deposition of disintegrated 

 matter; the lattei", consisting of yellow clay or brick-earth, sand and 

 rubble, etc., occurs in the interstices of the cliffs and on the lower 

 levels of the island. 



These superficial deposits are thus classified by Derrick in his 

 article on Guernsey cla3's (o^^. cit. ii. 212) : 



'*(!) Raised and ancient beaches; (2) Peat and the submerged 

 forests; (3) The sand deposits of the north-western coast ; (4) The 

 land-slips from the cliffs on the south and east coasts; (5) The clays 

 and loams ; (6) The varied soil of the island." 



The clays are of two kinds : 



" Kaolin clay is not a superficial deposit in Guernsey It 



IS a direct produce of the disintegration of certain veins in granitic 

 and gneissic rock, and is formed from the felspar which those rocks 

 contain. On our beaches bands of clay, or broad veins filled with 

 clay are rather numerous, the daily action of the tide hastening the 

 process of decay, as at Longshore and St. Sampson's." This clay is 

 used commercially under the name ' Butt clay.' " Clays forming 

 true superficial deposits are widely distributed and nowhere covered 

 by the rock or intersected by the veins, which rise toward the clay 

 and turn off horizontally beneath it." 



(5) Coiiji.fjurafiori of the Coast. 



The Island of Guernsey is a right-angled triangle : the east coast 

 forms one side, that of the south a second, while the third or hypo- 

 thenuse consists of the west, north-west, and north coasts, merging 

 imperceptibly into each other. The features of each side differ 

 markedly. 



The east coast is moderately sheltered and the climate mild. The 

 Islands of Herm, Jethou, and Sark, and the coast of Normandy in 

 the distance protect it fi'om rough weather to a great extent. The 

 largest opening on this side is Belgrave Bay. A roadway and wall 

 skirt the upper part of the shore. Northwards are St. Sampson's 

 Harbour and granite quarries ; beyond is the deej) and slveltered 

 creek, Bordeaux. In the other direction are Fermuin JJav and two 



