Geology Reference
In-Depth Information
explains how the principles of tec-
tonics and structural geology are
used in understanding present-day
and ancient mountain belts.
ancient orogenic belts - the Lower Pal-
aeozoic
Caledonides
of the British Isles,
the Mid-Proterozoic
Grenville belt
, and
the Early Proterozoic
Trans-Hudson
belt
of Canada. Finally, examples of
Archaean orogenesis from Canada and
Greenland are examined to explore the
question of whether plate tectonics and
orogeny operated in a basically similar
way in the very distant geological past.
useful in understanding the tectonic
context of certain structures; these are
summarised in the form of tables.
1
What is not included
This topic is not intended as a compre-
hensive survey of the whole subject,
and what is selected partly reflects
the author's subjective view of what
is most important, and also a desire
to keep the topic reasonably short.
Certain topics are omitted as not
directly relevant; these include the
interpretation of geological maps
- the
complex geometry of the interaction
between simple structures and the
three-dimensional ground surface - and
sedimentary structures
, i.e. bedding and
allied structures formed by the pro-
cesses of erosion and sedimentation.
2
3
Chapter 11: Examples of modern
orogenic belts.
Three typical exam-
ples are chosen from the present-day
orogenic belt system: the central
Himalayas, the Western Alps and the
Canadian sector of the North Ameri-
can Cordillera. In each case the struc-
ture of the belt is explained in terms
of its plate-tectonic context, and the
sequence of plate movements that
are believed to be responsible.
Appendix.
There are certain topics
of general geological interest, but not
directly relevant to structural geology,
which most geology students will
understand, but which might be unfa-
miliar to other readers. These include
the geological timescale, and the clas-
sification of igneous, sedimentary and
metamorphic rocks, which are often
Chapter 12: Ancient orogenic belts
.
The same approach as in the previous
chapter is taken to examples of more
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