Geology Reference
In-Depth Information
(a)
(b)
Figure 1.7.
(a) H. Cloos' diagram of fractures in a batholith: c - cross joints, l - longitudinal joints, f - flat-
lying joints, some of them stretching planes, r - rift, h - hardway, apl-c and apl-p are aplitic dikes
(sills?), and dashes are linear flow structures. (b) Quarrymen at the Porriño Quarry, South Galicia,
Spain splitting the rock along the rift.
location and course of weathering, erosion and eventual morphology. Granites of similar petrol-
ogy may give rise to different landform assemblages according to tectonic history.
1.5
PHYSICAL CHARACTERISTICS
Granite has an average specific gravity of 2.662. A cubic metre of granite weighs of the order of
2,658 kg, or almost 2 tonnes a cubic yard. Its physical hardness varies according to composition,
and principally according to the proportion and type of feldspars present. Despite its crystallinity,
