Rocks of El Gigante
and other nearby rock shelters
The wall of El Gigante is within a single layer
of ash-flow tuff. There are numerous holes (former pumice fragments?) and
angular fragments of andesitic or basaltic rock up to 2 cm across.
I'd have like to brought home some of this rock but my luggage
was packed with geophysical instruments. Perhaps next time.
In any event, I think we know the geological agent that carved El Gigante. This looks like a pothole.
So does this. El Gigante was once the underside of a waterfall. I think.
This cave, about 20 km to the south of El Gigante, however, is a real puzzle. It looks like a lava tube, only upside down, and is in tuff, not basalt. It ends abruptly some 8 to 10 meters into the hillside.
Another cave. These structures are several km south of Marcala.
This rock shelter, near the caves shown above, looks more like
the classical rock shelter formed by weathering and collapse of the roof.