The Toba eruption around 73,000 years ago caused a long term sudden drop in the already dropping temperature (see temperature charts for the last several hundred thousand years. Also there were several severe dips in temperatures in the 20 thousands BC. One was probably a huge Vesuvius eruption. Another about 22,000 ya was probably caused by the eruption of the Japanese volcano Sakarajima. It left a caldera over 10 miles in diameter and the modern volcano is on one edge of that crater. This Dryas event was apparently very widely spread and cause a major cooling lasting well over a thousand years.
Isn’t possible that some huge impact could have actually cracked the Earth’s crust along fault lines and caused volcanoes to spring up all over the globe or those that existed already to erupt in simultaneous manner, thus causing a global catastrophic temperature reduction?....................