These mountains comprise a series of currently inactive volcanoes that, over millions of years, deposited a thick layer (1500 feet) of volcanic lava, ash and mud.
(These mountains; comprise; a series of currently inactive volcanoes that, over millions of years, deposited a thick layer (1500 feet) of volcanic lava, ash and mud) (a series of currently inactive volcanoes; deposited; a thick layer)
These mountains a series of currently inactive volcanoes
comprise deposited
a series of currently inactive volcanoes that, over millions of years, deposited a thick layer (1500 feet) of volcanic lava, ash and mud
a thick layer