hrown up, preserve
a parallelism the one to the other.

These opinions, and others by which they are accompanied, are so adverse
to the method of interpreting the history of geological changes which I
have recommended in this work, that I am desirous of explaining the
grounds of my dissent, a course which I feel myself the more called upon
to adopt, as the generalizations alluded to are those of a skilful
writer, and an original observer of great talent and experience. I shall
begin, therefore, by giving a brief summary of the principal
propositions laid down in the works above referred to.[242]

1st. M. de Beaumont supposes "that in the history of the earth there
have been long periods of comparative repose, during which the
deposition of sedimentary matter has gone on in regular continuity; and
there have also been short periods of paroxysmal violence, during which
that continuity was broken.

"2dly. At each of these periods of violence or 'revolution,' in the
state of the earth's surface, a great number of mountain-chains have
been formed suddenly.

"3dly. The chains thrown up by a particular revolution have one uniform
direction, being parallel to each other within a few degrees of the
compass, even when situated in remote regions; whilst the chains thrown
up at different periods have, for the most part, different directions.

"4thly. Each 'revolution,' or 'great convulsion,' has fallen in with the
date of another geological phenomenon; namely, 'the passage from one
independent sedimentary formation to another,' characterized by a
considerable difference in 'organic types.'

"5thly. There has been a recurrence of these paroxysmal movements from
the remotest geological periods; and they may still be reproduced, and
the repose in which we live may hereafter be broken by the sudden
upthrow of another system of parallel chains of mountains.

"6thly. The origin of these chains depends not on partial volcanic
action, or a reiteration of ordinary earthquakes, but on the secular
refrigeration of the entire planet. For the whole globe, with the
exception of a thin envelope, much thinner in proportion than the shell
to an egg, is a fused mass, kept fluid by heat, but constantly cooling
and contracting its dimensions. The external crust does not gradually
collapse and accommodate itself century after century to the shrunken
nucleus, subsiding as often as there is a slight failure of support, but
it is sustained through