Reply to ‘Chicxulub impact predates K–T boundary: New evidence from Brazos, Texas’ Comment by Schulte et al

We appreciate this opportunity for further discussion of the Brazos, Texas, K–T boundary sequences and their timing with respect to the Chicxulub impact. Keller et al. (2007) used a multidisciplinary approach to document the stratigraphy, paleontology, mineralogy and geochemistry of the newly drilled Mullinax-1 core and a new outcrop sequence. Based on this multi-proxy dataset very strong evidence was presented that reveals that the Chicxulub impact predates the K–T mass extinction (Keller et al., 2007). Schulte et al. take issue with this approach and our findings largely because they believe that the Chicxulub impact caused the K–T mass extinction and therefore the K–T boundary must be placed at the impact spherule layer (Schulte et al., this volume; Schulte et al., 2006; Smit et al., 1996). We welcome this opportunity to clarify misunderstandings, misconceptions and misinterpretations of the K–T record in Texas and elsewhere. At the heart of our disagreements is the decades old controversy about the cause of the end-Cretaceous mass extinction. Schulte and collaborators have long argued that the sandstone complex, or event deposit, with impact spherules at the base in NE Mexico and Texas mark Chicxulub impact-generated