140 Notes on the Geology of Murray Bay, 



places in tlie vicinity of the bay, but they present a strange and 

 puzzling aspect to the observer. Proved by the investigations of 

 Logan and Hunt, to have once been sedimentary rocks, they 

 have been so changed by heat and chemical action, that they re- 

 tain no resemblance to the sands, clays, and limestones, of which 

 they were originally composed. They now appear as beautifully 

 crystalline layers, which have when in a yielding and flexible con- 

 dition, been bent and crumpled as if for long ages they had been 

 kneaded by the hands of Titans, so that it is diflBcult to form any 

 conception either of their original nature or arrangement. The 

 greater number of rocks are eloquent to the geologist of the history 

 of hfe in past periods of the earth, but these Laurentian beds pre- 

 serve an obstinate silence, only hinting in their flakes of graphite 

 and their crystalline limestones, that they have a story which they 

 cannot be persuaded to tell. Still they aff'ord very instructive 

 examples of the changes which may be eff"ected by metamorphism 

 in aqueous sediments, and they abound in interesting and curious 

 crystallized minerals. In the high cliff" commencing immediately 

 west of the pier, they are well exposed ; and at this place the or- 

 der of succession is as follows, apparently in ascending order, 

 though these beds are here so often inverted that little reliance 

 can be placed on apparent superposition. 



1. Gneiss of various colours and qualities, with both lime and 

 potash felspars, and containing beds of mica slate, with large no- 

 dules of garnet, around which the beds bend as if the garnets 

 had originally been foreign masses or pebbles. In some 

 places these beds hold bands or dykes of a coarse-grained red 

 felspar. These gneissose beds are of great thickness and occupy 

 the greater part of this long range of cliff's. They reappear on 

 the opposite side, at and beyond Cape Heu. 



2. White quartz rock, perfectly compact, with thin bands of 

 hornblendic and micaceous schist, and in the upper part with 

 some crystals of flesh-coloured felspar. This bed or a similar one 

 appears on the opposite side of the bay on both sides of Cape Heu, 

 where in one place it immediately underlies the Silurian beds, as 

 has been observed by Sir W. E. Logan, but it is clearly a member 

 of the Laurentian series. 



3. Impure crystalline dolomite, and light-coloured laminated 

 serpentine. These are only a few feet in thickness, and in some 

 places seem reduced to a few inches. Being the softest part of 

 these rocks, they form a depression in the cliff or reef, and are 

 often hidden by gravel or rubbish. 



