The wet weather has precluded most field work over the past few days; however the ground has now dried up enough for it to recommence. Following is a summary of the status of the ongoing work program.

Sedimentology of the Dakota Sandstone

Melissa Battler collected the last of her data on this unit during the overnight EVAs in the Everest rover (EVA 43 and EVA 45). While she is confident she has enough data for her honours project, there remains the opportunity for some additional data to be collected by other geologists during the remaining two weeks of Expedition One.

Regolith Terrain Mapping

I am confident that the main regolith-terrain elements of the MDRS landscape have been identified. The different elements can be combined into distinct RT units that allow the landscape at both the regional and site scale to be fully characterised by a single descriptor. An illustrated legend to the RT units of the MDRS field area is being prepared and will be available on the web site before the end of Expedition One.

Igneous Suite Sampling

Putative tuffs and igneous lithologies in relict gravels have both been sampled for Stacey Sklar. Should additional lithologies be recognised, these also will be collected.

Figure 1 - Dust storm on February 22nd.

Aeolian Features and Processes

No new data has been collected for Veronica Zabala since a video record of blowing sand and dust on February the 22nd (see Figure 1). The conditions have not been favourable for it. I hope to document aeolian features in the San Rafael Desert during phase 3.

Geomorphic Effects of Rain and Snow

Geomorphological processes in deserts are like war – shore periods of terror interspersed by long periods of boredom. The snow and rain of the past few days has therefore offered a rare opportunity to study a range of geomorphic processes in action.

The smecticitic clays of the Brushy Basin Member when wet swell up, confining the moisture to the top few cm. They also increase in density, as water is taken up by the clays. On steep slopes this wet heavy layer is subject to detachment from the underlying dry clays, forming small land slips. As a result slopes of the Brushy Basin Member are resurfaced during rain and snow. This obliterates surface features (such as human footprints) and transports material down slope, to be removed by water.

Figure 2 - Snowstorm on the 26th.

Figure 3 - Mini chaos feature approx. 1m across

Runoff was significant during the days of rain and snow. Most of the small creeks were flowing (Figure 2), although the larger washes did not. Numerous small washouts were cut across the access road to MDRS by following streams. One curious small feature about 1 m across (Figure 3) was formed when a silt sand layer was undermined by water discharging from underlying gravelly and. The resulting micro-landform bears a startling resemblance to the chaos features of Mars, traditionally related to melting ground ice.