Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 3 - By Alexander Von Humboldt And Aime Bonpland.
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I Was Fortunate Enough To
Discover The Types Of Each Group In A Region Where, Before I Visited
It, No Rock Had Been Named.
The great inconvenience of the old
classification is that of obliging the geologist to establish fixed
demarcations, while he is in doubt, if not respecting the spot or the
immediate superposition, at least respecting the number of the
formations which are not developed.
How can we in many circumstances
determine the analogy existing between a limestone with but few
petrifactions and an intermediary limestone and zechstein, or between
a sandstone superposed on a primitive rock and a variegated sandstone
and quadersandstein, or finally, between muriatiferous clay and the
red marl of England, or the gem-salt of the tertiary strata of Italy?
When we reflect on the immense progress made within twenty-five years
in the knowledge of the superposition of rocks, it will not appear
surprising that my present opinion on the relative age of the
formations of Equinoctial America is not identically the same with
what I advanced in 1800. To boast of a stability of opinion in geology
is to boast of an extreme indolence of mind; it is to remain
stationary amidst those who go forward. What we observe in any one
part of the earth on the composition of rocks, their subordinate
strata and the order of their position are facts immutably true, and
independent of the progress of positive geology in other countries;
while the systematic names applied to any particular formation of
America are founded only on the supposed analogies between the
formations of America and those of Europe.
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