76 Prof. Liveing, On the metaniorphism [Oct. 29, 



The rocks of Guernsey consist of two principal divisions. The 

 upper one is a sort of gneiss, consisting for the most part of layers 

 of imperfectly crystallized red felspar, (which has been erroneously 

 described as scapolite) inter-stratified with layers of qua,rtz, and 

 sometimes hornblende and sometimes mica. This forms the part 

 of the island south of a line from St Peter Port to Vazon Bay. To 

 the north of this line on the west side of the island the gneiss 

 passes rather abruptly into a pink-coloured, highly crystalline 

 syenite, consisting of felspar, quartz and hornblende, with here and 

 there a very little mica, shewing no trace of stratification, used for 

 building in the island but not quarried for export. On the east 

 side the gneiss passes, also somewhat abruptly, into a dark grey 

 syenite, consisting of hardly anything but hornblende and felspar, 

 sometimes shewing traces of stratification but in other parts wholly 

 devoid of any such traces. This grey syenite is largely exported 

 for paving the streets and macadamizing the roads about London. 

 The parts which have the crystals of hornblende disposed in strata 

 (often hardly noticeable in hand specimens) are split with tolerable 

 regularity and wrought for curb and pitching stones, while the 

 other parts where all traces of stratification have disappeared are 

 broken up for macadam metal. There are some places (e. g. in 

 quarries in low ground between Delancy Hill and Noirmont) where 

 hornblende predominates and where the grain is so fine and uni- 

 form that the stone works pretty freely in all directions, and they 

 break it into pitching stones just as it comes. 



Ansted, in his work on the Channel Islands, states that these 

 two divisions, the syenite on the north and the gneiss on the south, 

 are parts of one metamorphic system. He does not trace the evi- 

 dence by which he arrived at this conclusion, and at first sight it 

 was rather difficult to believe that the highly crystalline syenites 

 and hornblende rocks were parts of the stratified system seen in 

 the south of the island. A closer examination convinced me that 

 his statement is correct. In some places the gneiss may be traced 

 passing gradually into grey syenite. This is seen on the south 

 side of Yazon Bay near Richmont barracks : and further south 

 near Fort Grey there is a quarry in a very tough hornblendic 

 gneiss which seems to be the transition condition of the rock. 

 The junction of the red gneiss with the grey syenite is obscured 

 on the east side by the town and harbour, and inland by the 

 surface soil. However, on the shore of the small bay under Fort 

 George there is grey syenite apparently interstratified with the 

 gneiss. They form there a perfectly continuous formation. Patches 

 of grey hornblendic gneiss are seen in the island of red gneiss 

 on which Castle Cornet stands. All question as to the syenite 

 being a stratified rock metamorphosed is set at rest by the oc- 

 currence of a bed of stratified quartzite in it. This occurs in a 



