It is hard to say, the quote has all of the hallmarks of being a quote mine. When a creationist does not supply a link to the original source one could make a fortune by consistently betting that it is an example of quote mining.
I've seen it said that the relatively steep sides of the canyon
"Prove" it is young.
The way it is phrased in the quote" worn, should be"
is not geologist talk.
Our creos do not read books, take notes then
go back to original sources so of course the quotes
are chosen by a creosote.
A non scientists givingan opinion with no
evident basis for it, in a book for lay
readersc is not much of a basis for showing
yec / flood is or is not true.
Still, it made me curious about the rate at which the
canyon widens. It's five miles across now.
The dynamics involved in the slope of an eroding/
weathering rock face is probably pretty complicated.
A geologist who presented a research paper
analyzing these factors could probably show whether
there is some unaccountable anomaly.