Down to work...

Updated: July 19, 2000

Back Again -

Today our fieldwork started in earnest. We spent the morning tracing the boundaries of the Mahenge lake sediments and surrounding diatreme. The crater is surrounded by granitic basement rock of the African craton (Precambrian rock at the core of the continent). This grades into a tuffaceous unit (volcanic ash that has turned to stone) that then grades into the lake shales and mudstones.

Grasshopper in camp

The diameter of the entire crater is 710 meters, while the diameter of the lake is approximately 450 meters. Tracing lake sediments turns out to be more difficult than we first thought because of some post-depositional slumping and faulting, making it difficult to correlate stratigraphic units. We located several of the original pits dug by Mannard in the 1950's, and have begun to expand Pit 5c in the center of the lake in preparation for further excavation (this pit was dug in 1996 by Terry Harrison and his team). We have also begun to remove over-burden from two other sites along the Luwala River in hopes of finding samples near the lake margin.

We have hired 10 local men from Mwaru, the village located near our camp, for digging and other camp chores. We began splitting shales at one of the sites and already have found several fish and plant fossils, as well as what appears to be a crocodilian coprolite (fossilized dung). While we were working this locality, we heard a loud buzzing sound off in the distance. As we waited a huge swarm of bees passed over-head. We were considering running but our Tanzanian colleagues assured us that there was no danger so we stayed and watched them buzz past harmlessly.

Wildlife continues to fascinate-we have more bush babies visiting us tonight and have also seen a variety of praying mantis', walking-sticks, rock lizards (Agama) enormous grasshoppers, scorpions, centipedes, and beetles. Still no flamingo's though.

Today's report by Gregg Gunnell