A section of the sediment layers at the Cretaceous/Paleogene boundary from the Braggs Site in Lowndes County. Note the many small core holes bored into the boundary zone for testing samples of microfossils. Scientists were able to determine through testing that the sediments contained rare elements that are found in asteroids and other celestial bodies, providing evidence for the theory that mass extinctions at this time were caused by an asteroid impact.
Figure 11. Cretaceous/Paleogene Boundary
Photograph by David R. Schwimmer, all rights reserved