Goble et al.2008
Digital Elevation Models as Heuristic Tools

Digital elevation models use modern relief data collected by satellites, and
manipulation of these satellite images provides a novel tool to visualize &
ask questions about hominin paleo-landscapes. A sequence of well calibrated
diatomites in the Chemeron Fm near Lake Baringo, Kenya, indicates
precessional (23-ky) cycling of extensive & rel.deep lakes in the Rift
Valley c 2.5 Ma. But how deep & how extensive? T he nature of the exposed
diatomites suggests they formed at least 5 km from the shore of the lake,
which was up to 150 m deep. GIS methods facilitate the “filling” of a
digital elevation of the modern Baringo Basin to 150 m above the current
altitude of major diatomite outcrops. The “lake” produced by this means
extends the entire width of the Rift, from E to W, and gives a plausible
estimate of the lateral extent of these features. However, a significant
emergent land mass ‐ the Tugen Hills ‐ remains nearer to the diatomites than
the postulated 5 km. Other geological evidence suggests that the Saimo
fault, which has controlled uplift of the Hills, was mostly active after the
end of Chemeron deposition, currently recorded at 1.6 Ma. It is quite
possible that the Tugen Hills did not exist, at least not in their present
major form, at the time of these Pliocene lakes. Although modern
topographic controls on lake formation may not necessarily reflect those
that existed in the Pliocene, these simple approaches provide useful ways of
visualizing plausible hydrologic patterns in the Rift Valleyʹs past. The
models produced offer insights into the past geological structure of the
area, the nature of rifting, and provide a new means of thinking about how
early hominid landscapes have changed since the fossils were buried.