Geology Reference
In-Depth Information
(a)
(b)
Figure 7.12.
Acicular towers in (a) southern Greenland (Oen Ing Soen); (b) the Organ Mountains, New Mexico.
7.2
MASSIFS
Granite uplands are found in many parts of the world. Their morphology varies according to ele-
vation, degree of dissection, and climate. Much of the Labrador Plateau in Canada, for example,
comprises a high granitic plain characterised by low bosses and rounded hills (
Fig. 7.14)
which
stand in marked contrast with the Labrador Trough, a region of folded sediments and basic vol-
canics on which is developed ridge and valley topography. The region was covered by ice sheets
until a few thousand years ago. The ice sheets have left a legacy of a scoured etch plain, moraines and
basins of interior drainage, so that large areas are occupied by lakes and swamps; it is for good reason
