OF DYNAMICAL GEOLOGY— BAILEY. 189 
V. JOINTS, CLEAVAGE, ETC. 
The divisional planes referred to above are of such common 
occurrence in regions of metamorphic or partly metamorphic 
rocks, such as form so large a part of Nova Scotia, as hardly to 
deserve notice here. And yet their recognition and distinetion 
from each other and from planes of bedding is one of the most 
serious practical difficulties to be encountered by the field 
geologist, especially in the study of the Cambrian rocks of the 
southern coast. The quartzites of this system abound in joint 
planes, often causing them to divide into prismatic blocks, while 
the slates of the same system have in general a strongly pro- 
nounced cleavage structure. Both may be, and often are, much 
more pronounced than the bedding planes, so that strata which 
are really level-lying, or in low undulations, may present the 
appearance of being highly inclined. Such a condition of things 
is especially prominent over much of the country north of 
Caledonia in Queen’s County, where, were it not for the fact that 
the rocks are strongly banded or ribbanded with somewhat 
strongly contrasted colors, indicating the true planes of deposi- 
tion, mistakes might very readily be made as to their true posi- 
tion. Portions of the coast south-east of Lunenburg, where 
similar strongly ribbanded beds occur, afford other illustrations 
of the same fact. 
Besides the joints which characterize the massive quartzites 
of the Cambrian, or the granite by which the latter is invaded, 
it is proper to notice here the similar divisional planes found in 
the traps of Digby Neck, Briar Island, &c. Some of the columns 
thereby determined are illustrated in Plate v. (Part 1 of the 
present volume of the Transactions,) as seen at Israel Cove on 
the Petite Passage, and others much more remarkable occur 
along the south side of Briar Island. 
VI. METAMORPHISM. 
Almost every stage of the metamorphic process may be well 
studied along the coasts of the south-western counties. The 
quartzites, as might be expected, show the least evidence of 
