1. what is the k - t boundary?

Brief Explanations:

The K - T boundary, also known as the Cretaceous - Paleogene (K - Pg) boundary, is a geological signature that marks the end of the Cretaceous period and the beginning of the Paleogene period. It is associated with a major mass - extinction event, including the extinction of non - avian dinosaurs. It is characterized by a thin layer of sediment rich in iridium, which is thought to be evidence of a large asteroid or comet impact.

Answer:

The K - T (Cretaceous - Paleogene) boundary is a geological layer marking the end of the Cretaceous and start of the Paleogene periods, associated with a major mass - extinction event and characterized by an iridium - rich sediment layer.