New Mexico Geological Society Annual Spring Meeting — Abstracts

Speleothem growth in moisture-limited regions, such as the Guadalupe Mountains, New Mexico is a good indicator of past regimes of effective precipitation. While the Holocene is seen as a dry period in the southwestern United States, periods of stalagmite growth are helping to resolve the wetter episodes from the drier ones. The Pleistocene-Holocene transition, an important and interesting period in the southwestern United States, coincides with the Younger Dryas event, best-documented early human colonization, and extinction of some important megafauna. Six columnar stalagmites from three caves in the Guadalupe Mountains show growth beginning near the start of the Younger Dryas and ending abruptly in the earliest Holocene. This period of growth reflects overall wetter conditions for the southwestern United States from about 12,500
years ago to no later than 10,500 years ago. Lack of, or less stalagmite growth from about 14,000 to 12,500 years ago indicates somewhat drier conditions during this interval. Growth hiatuses show the onset of distinctly drier conditions around 11,000 years ago with no growth represented after 10,500 years ago. The climate remained significantly drier until the late Holocene. The period of most significant growth started during and extended a millennium beyond the Younger Dryas event. We conclude that, while overall wetter conditions prevailed during the Pleistocene-Holocene transition, there is a lack of synchroneity between the Younger Dryas event and effective precipitation in the southwestern United States.