﻿Yol. 64.] 



TWO EARTH-MOVEMENTS OF COLONSAY. 



305 



fine-grained chilled margins in contact with the syenite. The 

 secondary cleavage in the dyke is very conspicuous in the coarse- 

 grained portion, and is also well shown hy the elongation of the 

 black spots in the chilled margin. It is throughout vertical, or dips 

 at very high angles. Its distinctness from flow-structure is very 

 obvious, since it may be seen crossing the banding of the dyke at 



a very consider- 



Eig. 7. — Shetcli-map of the Kiloran si/enite intrusmi. ^^^^ angle. At 



(Scale : 6 inches = 1 mile.) ?^® southern end 



it strikes, m the 

 fine-grained por- 

 tion I^. 20° W., 

 and in the coarse- 

 grained W. 20° 

 N. ; a little north 

 of the bend it is 

 W. 15° -N., far- 

 ther north N. 

 30° W., N. 40° 

 W., and W. 25° 

 N. toKW. In 

 the adjoining 

 syenite of Eilean 

 Easdale there 

 are marked lines 

 of crushing and 

 shearing, accom- 

 panied by a rude 

 mineral arrange- 

 ment with a 

 trend W. 40° I^. 

 The great scar 

 of breccia and 

 ^'Pitching aatklm ia bedding, syenite which 

 forms the land- 

 ward continuation of Eilean Easdale is crossed by five lamprophyre 

 dykes. Three of these, which are of small breadth, from 6 to 8 inches, 

 show the secondary cleavage in a very marked way. Another, 

 which is very massive and about 4 feet broad, shows no cleavage 

 where it cuts the breccia and syenite, but its obvious continuation 

 can be seen to the south, in the schists, and there it shows a distinct 

 though not powerful cleavage. As the syenite is thus cleaved, and 

 is traversed by cleaved lamprophyres, and as the direction of this 

 cleavage corresponds fairly well with that produced in the adjoining 

 schists by the secondary movement, it is pretty clear that it must 

 be prior in age to the secondary movement. As an obvious further 

 test, we went carefully over the fragments of schist exposed in the 

 breccia, with the object of ascertaining if any had been affected 

 by the secondary folding and cleavage before being included in it. 



x2 



L -Lamprophyre. \ 'Dip of 1^ Cleavage. '^-GenerAl dip of crumpled 



Uf^aeaved £amprojAyre.'^'^''j^ Axial P/anescf^ 0C/eava^e. 



>A'Difi of Strata. 



Z'^^ folding. 



