Lawton et al. (2005) describe valley-like deposits in the continental to shallow marine La Popa basin northwest of Monterrey, Mexico, and interpret these as the result of Chicxulub impact induced-tsunami backflow. They further speculate that the thick siliciclastic units, known from the deep paleocanyons of the continental slope to the south and southeast, can also be explained as tsunami backflow deposits. We find no evidence to support this notion in their paper or in more than 45 exposures we examined to the south. Below we comment on their tsunami backflow interpretation and the lack of evidence from Mexico to Texas.  PDF