Charles Lyell, Historian of Time's Cycle - Time's Arrow, Time's Cycle: Myth and Metaphor in the Discovery of Geological Time - page 145

most of our coal. Superficially, they provide firm support for the
directionalist hypothesis of an inherently cooling earth.
Lyell admits the phenomenon—northern-hemisphere coal forests indicate
hotter climates during the Carboniferous (I, ch. 6). If an inherent secular
cooling caused the subsequent change, then uniformity of state is disproved.
But Lyell offers an alternative based on current processes (I, ch. 7). As sea
and land change position, climate alters in predictable ways. If the northern
hemisphere had become more and more continental since the Carboniferous,
then climate would become cooler as a result of fluctuating surfaces, not
inexorably cooling interiors. Lyell then tries to demonstrate (I, ch. 8) that
cooling climates in the northern hemisphere have been accompanied by
increasing continentality since the Carboniferous.
This alternative explanation preserves the crucial uniformity of state.
Interiors cooling from an original fireball are irreversible records of time's
arrow. But exteriors that cool because continents rise impart no inherent
direction to time, and permit no future extension to further frigidity.
Continents rise by uplift and fall by erosion in a smooth and nondirectional
way through the fullness of time, recording both substantive uniformities of
rate and state: "The renovating as well as the destroying causes are
unceasingly at work, the repair of land being as constant as its decay, and the
deepening of seas keeping pace with the formation of shoals" (I, 473). As
continents have emerged since the Carboniferous, they may yield again to
ocean in the future—and cooling is but one segment of a reversible cycle.
Lyell speaks of a "great year," or "geological cycle," and views falling
temperatures in the northern hemisphere since Carboniferous times as the
autumn of a geological succession that will see another summer.
The first three substantive chapters are, therefore, one long application of
Lyell's method to an apparent (and central) case of disconfirmation. He
probes behind appearance to render an admitted phase of cooling, occupying
most of geological time and a large part of the earth, as but one arc of a
grander circle.
Chapter 9 then applies this reasoning to the greatest problem for any
supporter of time's cycle—the apparent increase in life's com-