Within its confines can be seen the remains of volcanic ash deposits spewed out by a dozen active volcanoes that rumbled in this area some 80 million years ago.
(volcanic ash deposits; spewed out; by a dozen active volcanoes) (a dozen active volcanoes; rumbled; L:in this area; T:some 80 million years ago)
volcanic ash deposits a dozen active volcanoes
spewed out rumbled
by a dozen active volcanoes
L:in this area T:some 80 million years ago