1881.] Prof. Liveing, On the rocks of the Channel Islands. 123 



of fusion, assisted by the action of water or steam and perhaps 

 other gases. Further observations made during last summer, 

 chiefly on the rocks of Serk and Jersey, tend to confirm the con- 

 clusions previously arrived at, and at the same time bring out 

 some fresh points which appear to be of sufficient interest to lay 

 before the Society. 



On Guernsey I have little to add to what I said before, except 

 to point out that in the section which I gave, the strata should 

 have been represented as bending downwards on the S. side far 

 more abruptly so as to become nearly vertical in that part of the 

 island. 



The geology of Serk is very simple, at the same time very 

 characteristic, so that it is an excellent commentary on that of 

 the other Channel Islands. Serk is a table-land elevated about 

 400 feet above the sea-level. On the East and West sides, that is 

 the sides which form the longer dimensions of the island, the table 

 ends in precipitous cliffs, but at the North and South ends it falls 

 more gradually to the sea, ending in long promontories continued 

 for some distance by detached rocks. The island of Brecqhou 

 forms a similar prolongation with a gradual slope to the sea on the 

 West side, and may really be considered as part of Serk, from 

 which it is separated by the narrow Gonliot pass only about 80 

 yards wide. The cliffs are on all sides intersected by deep ravines, 

 sometimes by chasms with sides absolutely vertical, and are per- 

 forated at the sea-level by numerous, often deep, caves. These 

 features are, of course, the natural consequences of its geologi- 

 cal structure. The mass of the island is formed of a crystalline 

 hornblende schist cleaving readily parallel to the bedding, and 

 making an excellent building material in everything but its colour 

 which is coal-black. This schist rests, as seen at one place only, 

 namely on the shore at the Port du Moulin on the N.W. side, on 

 a stratum of grey syenite or syenitic gneiss. Upwards the schist 

 passes into a more compact rock consisting of alternate lamina?, 

 of hornblende and of felspar mixed with a little quartz. This 

 again passes rather abruptly into a grey syenite in which the 

 bedding can be traced for a short distance upwards and is then 

 lost for a considerable thickness. The greater part of little Serk 

 is composed of this granitic rock closely resembling that of the 

 extreme north of Guernsey, and not unlike that of Herm which 

 supplied the steps at the foot of the Duke of York's column in 

 London. The originally stratified character of this syenite is how- 

 ever noway doubtful, for the bedding can be traced in it in many 

 places, and at Port Goury in the South end of little Serk a thin 

 bed in it crops out which has a slightly different mineral cha- 

 racter, is distinctly bedded, and being pervious to water has under- 

 gone more decomposition than the rock above and below it, and 



