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HOW TO MAKE A OEOLOGrICAL SECTIOX. 
By Peopessok B. T. AXSTED, M.A., F.R.S., Foe. Sec. G-. S. 
OME of our readers may perhaps wouder what can be said on 
a subject so simple as this; others may think time thrown 
away in reading an article that professes to teach a lesson in 
practical geology best learnt in the field. However this may 
be, there is much worth recording even in so simple a matter 
in field geology as the making of a section, and much that may 
be taught by description. Let us see how sections are made, 
what they suggest or teach, what varieties there are, and what 
are the faults and mistakes sometimes made in making use of 
such representations of nature. 
It is impossible to take a step in geology without recognising 
the great facts of stratification and disturbance of stratification. 
That almost all deposited rocks are stratified, or, in other words, 
are placed in successive layers or strata one above another, is a 
great fact in nature that is recognised in every quarry and every 
cliff. But it is equally certain, that, whenever we see stratified 
rocks, they have been lifted up to a considerable height above 
the bottom of the water where they were originally deposited. 
This change of position, due to mechanical elevation, has pro- 
duced in most cases either a tilting of the strata, or a fracture 
or dislocation of some of them — in some cases both these results. 
It is of course possible that a very large tract of country should 
be upheaved at once, so that the greater part of the strata 
should remain nearly horizontal. But this apparent horizontality 
may also be the result of several movements of upheaval. 
Shaft sections of mines or quarries, road or railway cuttings, 
cliffs, river banks, or even ditches, often afford sections illus- 
trating the arrangement of the strata. Such sections, how- 
ever, are not strictly geological sections. They enable the 
practical geologist to take observations from which he can learn 
the real dip and strike of the strata, and their thickness ; and 
they become geological sections when they lay bare the order 
of stratification in a recognisable and instructive manner for a 
sufficient distance, and are nearly at right angles to the strike of 
