One of the major reasons we've assembled a group of sedimentologists and paleontologists is to better understand the succession of rock sequences in the general vicinity of Caldera. If you scope out a Google maps/Earth image of the area, you can see multiple adjacent basins that are full of marine sediments. Some of these basins have ashes (great for radiometric dating), others not; some also have diatomites, which are compact and (usually) easily identifyable layers that can be important for biostratigraphic correlation.
Ultimately, we're interested in establishing a robust stratigraphic framework of the rocks that make up the Bahia Inglesa Formation, so that we can better know the origin of familiar members from today's Humboldt Current (e.g., sea turtles, sharks, dolphins, penguins), as well as the extinction of bizarre ones (e.g., walrus-convergent dolphins and aquatic sloths).
This aspect of work is fairly cerebral (as opposed to sheer brawn of an excavation) -- you're constantly checking your assumptions and interpretations against the rocks before your eyes. Here are some snaps of our work:
NDP, pointing to large rip up clasts within an immense conglomerate near the base of the Bahia Inglesa Formation. It is thought that the conglomerate represents a sudden and rapid flow of debris in a submarine canyon-like environment, possibly generated by a tsunami. (Photo JF Parham)
The group continues to measure the thickness of the rocks above the conglomerate from the first photo, along the seacliffs near Los Chorillos, a site south of Caldera. The general geomorphology of this sequence looks strikingly similar to the Pacific coast of South America elsewhere, most notably in Peru. (Photo JF Parham)
Now inland from the coast, the group continues to discuss how to interpret the sandstones and siltstones that form the Bahia Inglesa Formation. Left to right, Rubilar-Rogers; Le Roux; NDP; CSG. (Photo JF Parham)
Here the group sits to directly at the Bahia Inglesa Formation's so-called bonebed. Our preliminary work has led us to conclude that there's actually several bone-bearing horizons in the area, some of which are associated with hard, resistant, and phosphatized surfaces called hardgrounds. Such surfaces may represent a prolonged period when only large objects, like the bones of dead seabirds, fish, sharks and marine mammals were deposited on the seafloor, with no overlying sediment covering them. Our work focuses on correlating these hardgrounds at one exposure to another, over a large geographic expanse. (Photo JF Parham)
We work from sunrise to sunset, trying to maximize our daylight hours. We've been lucky in having mild to chilly mornings and early evenings, bookending sunny midday hours. You can get away with long sleeves this time of the year, but be sure and drink lots of water because it is dry.