It is true that the model as proposed for continental drift was not
physically possible. However, the evidence that it had happened in some
other fashion was strong.
Lyell did argue for a strict constancy of present processes into the past,
an extreme of uniformitarianism that has long been recognized as too rigid.
Ironically, some of the "proofs" of a young earth are based on such
extreme uniformitarianism, even as uniformitarianism is labeled as an
atheistic premise in the same book.
David C.