This marsh was formed by a high, broad valley that allows the Williamson River to flood thousands of acres, both on and off the refuge.
(This marsh; was formed; by a high, broad valley) (a high, broad valley; allows; the Williamson River to flood thousands of acres, both on and off the refuge) Context(a high , broad valley allows,List([25, 57))):(the Williamson River; to flood; thousands of acres)
a high , broad valley allows,List([25, 57))
This marsh a high, broad valley the Williamson River
was formed allows to flood
by a high, broad valley
the Williamson River to flood thousands of acres, both on and off the refuge
thousands of acres