Day 6 started earlier than normal, as we were required at the foot of the trail up La Soufriere, St Vincent’s active volcano, at 8 in the morning. Our guide Brace (from the Soufriere Monitoring Unit) rocked up slightly late, with only trainers for footwear! (Which later proved to have much better grip than my boots….). After a short drive through the banana plantations to the foot of the volcano, we began our slow and sticky climb.
The path proved to be surprisingly well maintained, and the cloud cover sheltered us from the worst of the sun. We made rapid progress, pausing for a break just over halfway up at the valley shown below.
Brace was eager to point out that we would be surprised by the size of the crater and lava dome that awaited us at the top, and he was definitely right! The lava dome that takes up most of the 1.6 km diameter crater is over 100m high, and on one side shows yellow sulphur deposits from recent degassing. Once a year, the Soufriere Monitoring Unit staff descend into the crater to make gas measurements, though the tricky and long path down meant that we weren’t able to access the crater floor on the day.
On our way down, we stopped to collect even more samples from the 1902 eruption, from well exposed deposits in ravines next to the trail. These yielded even more cumulates with attached host lava, and another monster cumulate almost equalling “King Vincy” in size! We were also able to get in situ samples from what we believe to be the 1580 eruption (from stratigraphic logs), adding another unit from the volcano’s history to the study.
Heading back, we stopped by a tempting looking roadcut through the Yellow Tephra formation, and within seconds found several useful samples in an extremely cumulate rich layer. This took us to a grand total of 100 samples for the trip! This means that we now have cumulate and juvenile magma samples from 4 different units from La Soufriere, as well as a range of mafic magmas erupted on the island. After a long evening session of more describing, packing and taping up boxes of rock, we were ready to send our new cumulate collection back to Durham.