216 GUERNSEY CLAYS. 



beneath is so gradual, that it leaves the impression that a 

 continuous decay of the rock in situ had produced all the 

 present conditions, as though the rock in these spots had 

 consisted almost entirely of quartz and felspar, the infiltration 

 of water had changed the felspar into clay, the freed quartz 

 particles had sunk through it on to the gravel below. Quan- 

 tities of such fine quartz particles can be seen in the clay in 

 the cutting on the hill-side beyond St. Andrew's brickfield, 

 but they do not form a bed or even lines. In nearly all the 

 pits an irregular line of angular fragments of local rock occurs 

 in the lowest part of the clay ; these generally lie on their 

 broader faces. 



Clay is formed of the impalpable particles of solid matter 

 which have been carried down by rivers or violent currents. 

 Rapid streams loaded with solid matter on entering the still 

 waters of a lake or the open sea, are checked in their course, 

 and drop, first, the heaviest and largest materials they had 

 been carrying along, fragments of rock, pebbles, &c, then the 

 smaller particles resembling sand would be deposited, and 

 lastly and at a greater distance from the shore, those light 

 impalpable particles which go to form clay. 



Guernsey rocks contain all the materials requisite for the 

 formation of clay, so that the beds here may have been formed 

 in lakes or quiet reaches of the sea covering the whole or part 

 of what is now the surface of the island. But clay is found on 

 the highest ground in the island, if then it were deposited in 

 water covering those parts there could be no large extent of 

 land within the present area of the island from which rivers 

 could have come. Are we to suppose then that the deposits 

 were formed when Guernsey was much larger than at present, 

 when perhaps it formed part of land continuous to the con- 

 tinent ? This theory seems to me to lack probability, and not 

 to meet all the facts of the case. Preserving our present 

 relative level, and submerging Guernsey to allow the deposit 

 of clay in its highest part, we should have to imagine a river 

 running west from high land in France ; how far off this high 

 land would be is a matter of conjecture, but unless the levels 

 have changed there would be so much submerged land to the 

 east of Guernsey that the clayey particles would have been 

 precipitated much further to the eastward; beside, such a 

 river could not still carry in it the stones now embedded in 

 the clays (of which I show specimens) ; and how comes it that 

 the stones are similar to our local rocks ? On the other hand 

 there is special difficulty in accounting for the flints in the 

 Vrangue clay ; these must have been swept off a surface where 



