Punta Moreno, Isabela

Isabela (fka Albemarle) is by far the largest island of the Galápagos archipelago. It is made up of six shield volcanoes which have, over the course of geological history, joined together. The first visit we made was a walk over lava fields, checking out a few brackish lagoons like this one on the way.

There are very few plants which grow on the almost bare lava which covers this area of Isabela.
This one is called Lava Cactus, Brachycereus nesioticus. It is one of the first plants to colonise lava flows. Young stems are yellowish, older ones turn grey-green, then eventually black, and each flower only lasts for a few hours.

Much of the lava is of the type which is called 'pahoehoe': the Hawaiian word for rope-like.
Marylee Stephenson describes its formation thus:

Pahoehoe "... is formed when the superheated lava cools more rapidly on its surface than on the 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 flow".