Mountain Wetlands, Rivers, Permafrost, and Paleo Fires: A Multi-Proxy Story of Late-Quaternary Climate Change in the San Juans of Colorado, USA

Keywords: Mountains, geomorphology, paleoenvironment, soils, Colorado
Abstract Type: Poster Abstract

Abstract

Our geomorphology and soils research in the San Juan Mountains and adjacent high-elevation San Luis Valley of Southern Colorado has been ongoing for over a decade. We use multi-proxy evidence collected from wetlands, forests, alpine areas, river systems, and soils to piece together how climate has changed from the late Quaternary through modern times. A radiocarbon- and optically stimulated luminescence- (osl) controlled study of two paleo wetlands in the Monte Vista National Wildlife Refuge at 8,000 ft elevation shows pollen species and groundwater levels fluctuating between cooler, wetter environments and warmer, drier conditions through the late Quaternary with a modern warm and dry signal. Temporally controlled data from moraines, kames, glacial outwash deposits, and fluvial terrace sediments also suggest a cooler and wetter Younger Dryas (YD) and a fluctuating Holocene climate with mountain river systems entrenched in glacial cobbles for the past 9,000 years. Temporally controlled alluvial soil and sediments combined with pollen data suggest major paleo forest fires at intervals of 200 to 300 years from 860BP until present. A synthesis of these studies suggests that a multi-proxy approach to paleoenvironmental research can help draw connections between paleo and modern climate change. Specifically, our study glacial and periglacial systems connect to paleo wetlands and and paleo fires and tie the late-Pleistocene and Holocene geomorphic story to current environmental changes, while our study of beetle-kill forests ties the modern wetland pollen data to a concrete, highly visible example of the modern signal.