Rock pieces, some of them pretty big, fall on the Parkway in the winter as a result of water freezing and thawing, but this rock is the biggest single rock I've seen on 
(some of them; fall; on the Parkway; T:in the winter; as a result of water freezing and thawing) (this rock; is; the biggest single rock I've seen on) (the biggest single rock; 've seen; I)
some of them this rock the biggest single rock
fall is 've seen
on the Parkway T:in the winter as a result of water freezing and thawing
the biggest single rock I've seen on
I