One of the most intriguing features along our Tuesday morning's panga ride is the hundreds of "lines" that cut through the outside flanks of Ecuador Volcano. These features are known as dikes. A dike is an intrusive sheet that breaks through country rock layers, usually at a high angle.
Ecuador Volcano is one of the six volcanoes that form the largest island in the Galapagos: Isabela. Ecuador is the main shield volcano, but on its collapsed flanks there are several parasitic cones. One of those is "Punta Vicente Roca", a tuff formation eroded by the sea, at the southern tip of Ecuador Volcano.
Tuff is compacted ash; it is brownish in coloration and very easily eroded. Our picture shows the black and younger lava that intruded through the tuff, it is a very clear dike of basalt.
This is an area of sunfish and penguins, a place where we can admire enormous, well-fed marine iguanas, diving boobies, sea turtles and fur seals. But none of that overshadows the impressive geology of the site.
