A SUMMER RAMBLE AMONG THE HEBRIDES. 101 



enclosed mineral, and the pale flesh-colour of the ground, fre- 

 quently furnishes specimens of great beauty. In some pieces 

 the tremolite assumes the common fan-like form ; in some, 

 the crystals, lying at nearly right angles with each other, 

 present the appearance of ancient characters inlaid in the 

 rock ; in some they resemble the footprints of birds in a thin 

 layer of snow ; and in one curious specimen picked up by 

 Mr Swanson, in which a dark linear strip is covered trans- 

 versely by crystals that project thickly from both its sides, 

 the appearance presented is that of a minute stigmaria of the 

 Coal Measures, with the leaves, still bearing their original 

 green colour, bristling thick around it Mr Elder showed 

 me, intercalate^ among the gneiss strata of a little ravine in 

 the neighbourhood of Isle Ornsay, a thin band of a bluish- 

 coloured indurated clay, scarcely distinguishable, in the hand 

 specimen, from a weathered clay-stone, but unequivocally a 

 stratum of the rock. I have found the same stone existing, 

 in a decomposed state, as a very tenacious clay, among the 

 gneiss strata of the hill of Cromarty ; and oftener than once 

 had I amused myself in fashioning it, with tolerable success, 

 into such rude pieces of pottery as are sometimes found in 

 old sepulchral tumuli. Such are a few of the rocks included 

 in the general gneiss deposit of Sleat If we are to hold, 

 with one of the most distinguished of living geologists, that 

 the stratified primary rocks are aqueous deposits altered by 

 heat, to how various a chemistry must they not have been 

 subjected in this district ! In one stratum, so softened that 

 all its particles were disengaged to enter into new combina- 

 tions, and yet not so softened but that it still maintained its 

 lines of division from the strata above and below, the green 

 tremolite was shooting its crystals into the pale homogeneous 

 mass ; while in another stratum the quartz drew its atoms 

 apart in masses that assumed one especial form, the feldspar 

 drew its atoms apart into masses that assumed another and 



