Charles Lyell, Historian of Time's Cycle - Time's Arrow, Time's Cycle: Myth and Metaphor in the Discovery of Geological Time - page 174

The Uniformity of Rate
Since Lyell finally abandoned time's cycle for life's history, this linchpin of
his original vision has dropped from sight; few practicing geologists are
aware that Lyell ever espoused uniformity of state, and they do not
understand the theory of their founding father because they do not recognize
its keystone.
But gradualism, or uniformity of rate, experienced a different fate. If
anything, Lyell strengthened his commitment to this other substantive
uniformity by accepting evolution in Darwin's gradualistic version.
Uniformity of rate has therefore persisted to our present day, not always
embraced by geologists, but understood as Lyell's vision. Unfortunately,
Lyell's trope of rhetoric has also descended in unmodified form—his
conflation of method and substance. For more than a century, many
geologists have been stifled— the range of their hypotheses falsely channeled
and restricted—by a belief that proper method includes an a priori
commitment to gradual change, and by a preference for explaining
phenomena of large scale as the concatenation of innumerable tiny changes.
Lyell's own attempts to base a research program on uniformity of rate failed
when his statistical method for zoning the Tertiary foundered upon
inconsistent criteria among experts for the designation of species (Rudwick,
1978) and, especially, when he could not extend his method beyond the
Tertiary to formulate a general practice rooted in time's stately cycle. If
uniformity of rate really applied to the introduction of species—if life's
beanmaster introduced and removed these basic units at a stochastically
constant rate—then Lyell could have extended his method to the abyss of
time. Few modern species could be found in Eocene rocks (defined as 3
percent of modern forms), and none in earlier strata. But, in principle, new
baselines could be established to push Lyell's method further back—one
might, for example, tabulate the list of Eocene species and then zone the
Secondary strata by percentage of species still living in the Eocene.