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'T'&'!': Natural channels rarely end in a perpendicular 'T'-shape for obvious reasons. In the image on the right, the crater appears to have extremely steep walls and a flat floor. The elongated shape is incompatible with crater formation mechanisms because of their explosive, rather than excavating, nature. No “source' or “sink' is available for excavation to have occurred by flowing liquid. Source for “T': SP243004.jpg.