The two most recent eruptions, which began in 1902 and 1929, produced volcanic spines.
(The two most recent eruptions; began; T:in 1902 and 1929) (The two most recent eruptions, which began in 1902 and 1929; produced; volcanic spines)
The two most recent eruptions The two most recent eruptions, which began in 1902 and 1929
began produced
T:in 1902 and 1929
volcanic spines