The K-T boundary has received intense scientific study in recent years as researchers try to understand the changes between the time periods. Big Bend’s rocks are important to this study because the K-T boundary is well preserved, is clearly exposed, and is one of the southernmost exposures of terrestrial sedimentary rocks of that time period. On a geologic scale, Big Bend is relatively close to the well-publicized Yucatan meteor impact point, which has recently gained favor as an explanation for the abrupt changes seen at the K-T boundary.
It is important to understand that even if the Yucatan meteor is shown to be the coup de grace that finished off many Mesozoic species, it is only a small part of the story. Indeed, the fossil record clearly shows that these animals were gradually declining in diversity, with numerous species going extinct during the Upper Cretaceous, over millions of years. During this time the world’s climate was changing as shallow seas were draining, mountains were being built, temperatures were cooling, and perhaps wind speeds were increasing. Although a meteor may have finished things with a bang, the real culprit in most of the Cretaceous extinctions was long-term global climate change.
Did You Know?
Air temperature changes by five degrees for every 1,000 feet of elevation you gain or lose; temperatures in the High Chisos Mountains in Big Bend National Park can be 30 degrees cooler than temperatures along the Rio Grande. More...