As your boat passes by Santiago Galapagos on its various trips and as it pulls into Sullivan Bay itself, you often see wedges of black lava cutting across the island’s reddish slopes. Santiago is a classic volcanic island, rising to a dominant cone nearly 1000 meters tall at its northwest side. It also has many smaller cones projecting from its major slope, some having craters and others not.
Sullivan Bay Galapagos Islands
Sullivan Bay is the place to be reminded of how active the volcanic earth building is in the Galapagos. This site features a lava flow slightly more than 100 years old. It is a great swath of lava that oozed down to the sea, curling around small cones that came before it, adding land at the sea’s edge where there was no land before. There is a lot to be learned here about land-building processes, but first there is the feeling of astonishment and mystery as your walk over the shiny black lava fields.
The landing is a dry one onto a small ledge. You should wear lightweight running shoes to protect your feet on landing and on the fairly smooth but sun-baked lava flow. (You guide may have toughened bare feet, but visitors rarely do). Watch for penguins near the landing area. You may be lucky.
As your enter the lava field, what looks from a distance to be monotonous paving turns out to be a multilevel terrain of sheer fascination. It is like being in immobile black batter – 110 square kilometers of it. The proper name for this kind of flow is pahoehoe, pronounced with five syllables (“pa-ho-e-ho-e”). the word is Hawaiian for “ropey”. It is used by scientists everywhere to describe the same type of lava flow and surface character. It is a very apt word, conveying very well the shapes the lava takes as it flows fairly slowly, hardening into fans and swirls and protrusions of roughly parallel rope-shaped strands.
This kind of pattern is formed when the superheated lava cools more rapidly on its surface than in its interior. The lower, hotter part continues to flow and the upper parts begin to drag as they cool and harden, this uneven cooling gives the flowing mass its characteristic fan shape, with a series of curving creases roughly perpendicular to the direction of the flow. The flatness of the land over which it flows (the lava tends to separate and flow around obstacles such as earlier-established volcanic cones) and the fact that this flow went rather slowly overall (it was not the result of explosive volcano-buildin) allowed the flow to meander. There are fans a few inches in diameter as well as ones several meters across; they all interweave and overlap in the most marvelous fashion. Some of them look very much like other things; one part you’re likely to see the one called “pig guts” by the locals, and there’s no arguing the accuracy.
Stay tuned for more on my Galapagos travel journey...