I actually don’t understand the meaning of that sentence in Dickens fully either.

> As much mud in the streets, as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill.

Why does “as if the waters had but newly retired” mean there’s a lot of water (and thus mud)? “As much mud as” clued me in, but I don’t get this part.

And apparently it’s also referencing not just some flood but the flood of Noah’s Ark from the Bible, which is why you might happen to see a dinosaur because it was such a long time ago. I guess I don’t come across many opportunities to think of / that remind me of Noah’s Ark because I didn’t think of that either.