Explained to me as 'extinction layer' being exposed.

[CJRocks101]

Weekend spent with kind friends who introduced me to a different landscape.
Yucatan was mentioned (Chicxulub crater). 63 (or 65?) million years was mentioned. Extinction layer was mentioned.
It was different than anything I've ever seen ...
They pointed out that I was walking over ammonites. ... ??? !!!
Sure enough ....