The end of the cretaceous: sharp boundary or gradual transition?
Evidence indicates that the Cretaceous-Tertiary boundary is very sharp, and, within the limits of resolution, it is apparently synchronous at the various boundary localities. Arguments to the contrary, particularly those of Officer and Darke, are shown to invalid.
Alvarez
W
W
Alvarez
L W
LW
Asaro
F
F
Michel
H V
HV