|Friday 20th September
Savannah Soil Pit digging began after breakfast. By the end of the day the pit was complete down to a depth of 1 meter. The major part of the digging was done by PeterH but everybody participated. The pit was roomy enough to move around in and to squat down in order to examine the lowermost part of the pit. Drilling began with the soil auger to penetrate what eventually amounted to a total depth of 3 meters. The soil profile shows color change with depth related to the migration of iron downward in the soil column. The auger head is shown with wet fine sandy/clayey soil. The hands indicate the red aterite nodules.
TimK and the trail cutters take the journalists for a walk away from camp and toward the crater center to get an idea of the terrain. An important feature of this trip was reflected in Carlos description of pirrhana grass (called razor grass by the locals). Characterized by stiff sawtooth edges on the individual blades the pirhana grass proved to be brutally efficient at lacerating the skin and even cutting through clothing.
Holly, Jim and Bob accompanied by Aaron, Peter, Erin, Paulo, and Maria walk across the forest from Palmasola, arriving in the late afternoon. The biologists were busy with their nets and traps (A / B) to capture specimens of the local fauna. The second WEBCAST features PeterW and Gunther on Magnetism and Magnetometer data collection. They discuss the fact that the Iturralde structure (33a) is located at the geomagnetic equator. Consequently the Equatorial Electrojet (EEJ) which is a dawn to dusk current system active in the vicinity of the geopmagnetic equator gives rise to unique base station magnetic records (33b). A basestation was established each day that magnetic traverses were done, This basestation data was then subtracted from the traverse data. (33c)The magnetometer/biology traverse tracks indicate the coverage during excursions away from the crater camp.
Tonight, a bushfire was clearly visible to the sotheast of our camp. We first became aware of the forest burning during the helicopter flights from Riberalta to Cobija and then on to Puerto Araona. The intensity of this burning became more visible the closer we were to the Brazilian border with Bolivia. Any concerns about the approaching fire were soon quenched by an intense tropical rainstorm that drenched the entire area and sent the expedition in a mad scramble for shelter.