Breccia at Mawrth: polygonal breccia & breccia in elongate pods Latitude/longitude: 1) 24° 8'40"N, 18°53'55"W 2) 24° 8'55"N, 18°53'40"W Rationale: Interesting crosscutting relationships between polygonal breccia & breccia aligned in elongate pods. Both light &dark polygons at 1; breccia pods that crosscut topography at 2. Morphology and Mineralogy: Polygonal terrain with variable albedo contrasts that may reflect differential weathering/cementation. Excellent expression of breccia pods tentatively interpreted as impact-induced brecciation. Near boundary between Al and Fe/Mg clay minerals (see Al-Fe border target). What will the rover specifically do? Study: crosscutting relationships to determine timing of polygonal breccia formation relative to breccia pods & surface exposure; geometry of breccia pods to test their origin; relationships btw breccia types, weathering, & mineralogy.

PSP_007612_ m Differential high and low erosion of polygon centers vs. edges & variable polygon sizes. They also appear to postdate larger-scale breccia, possibly similar to that in pods (like that in sub-site 2). This is near the Al – Fe/Mg clay mineral boundary, and origins of these clays may correlate to changes in texture in this area. Sub-site 1

Arcuate breccia pods from HiRISE image PSP_006676_2045 draped on HiRISE DEM. Contour interval is 2 m in B with black shading extending downslope; shading width is inversely proportional to the slope. Breccia blocks concentrated between arcuate fractures dominate outcrop patterns. Blocks become smaller upslope in some cases (black arrow) and downslope in others (white arrow), which suggests that they do not represent collapse of layers. MSL can use crosscutting relationships here to determine the origin of the breccia and evaluate whether it reflects depositional layering or fracturing related to impact. Sub-site 2