FMARS Sponsors	Geology Report - July 30, 2005 Tiziana Trabucchi Reporting Geology Observations from EVA-19 Narrative: For EVA 10.19 we planned to go SW from the hab. We had two different objectives. One of these was to find the outcrop known as "Impact Breccia," and the other was to discover new fossils at 277 Hill zone. We kept going SW from the hab and we traveled for one hour through polygonal soils, muddy soils, and clastic deposits of different sizes. We saw two huge blocks of rock lying on the slopes of the hills in a chaotic way, because they rolled down from the top of the hills. They didn't present any stripes (grooves) from glacial dragging. We also went across many streams and two small lakes. In the area near the small lake we found a lot of fragments of possible chert-bearing carbonates. Another geologic aspect of that zone was that the hills were covered with clastic fragments, and often the layers were inclined. Near the small lake the layers were inclined roughly 45 degrees and the dip was East, in the same direction of the side hill. This fact emphasized the layers of erosion. The layers from these hills were strongly degraded due to meteorological and mechanical erosion (from the temperature difference, when the water freezes and thaws and re-freezes in the pores and in the fractures). From this process the rocks break. We stopped at 277 Hill, walked up to the creek canyon, and then climbed up the cliffs. We saw many algae structures, a coral colony, and a lot of shell tracks. These rocks were generally deeply degraded, and the embedded fossils were hard to recognize. Our second objective was to find one outcrop of Impact Breccia. We stopped with the ATV's when the soil started to become muddy, and we kept going on foot. Across the creek we climbed a muddy grey hill with many water patterns on it. We collected several samples, of different colours, grey and black, and we discovered two sites of white beautiful crystals, on the top of the hill. They look like evaporite deposits (probably gypsum) and were vertically aligned. The structure of these deposits looks similar to "diapiric" stuctures and often these diapiric evaporites can be seen on the intersection between two faults. From the map in this area there is more than one fault. Many of the blocks and grey fragments showed structures like shatter cones. I'm particulary surprised about the number of these "supposed" shatter cones, and about the fact that if viewed with the magnifier they are full of microholes! Further analysis will be done at researchers' home institutions. Return to Daily Index Page
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