Magnitude of Quaternary temperature fluctuations inferred from relict paleosols and periglacial features, Waterton-Glacier Park area, Montana and Alberta
Dr. Eric T. Karlstrom
Emeritus Professor of Geography, California State University, Stanislaus
Because particular kinds of soils and periglacial features form under particular climatic regimes, magnitude of past climate change may be estimated in areas where relict paleosols and periglacial features are not in equilibrium with the present climate. Relict (interglacial) paleosols in Quaternary sediments near Waterton-Glacier National Parks most resemble fersiallitic soils (Paleudalfs, Palustalfs, and Paleudolls) of the southeastern U.S., where mean annual temperatures (MATs) are at least 6 to 8°C warmer and mean average precipitation (MAP) is at least 40 cm greater than those of the Waterton-Glacier Parks area today (MAT is ~4.2°C and MAP is ~50 cm). Relict periglacial features in this region, including ice-wedge casts, record much colder glacial conditions. Because ice-wedges form in continuous permafrost where MATs are -6°C or colder, occurrence of ice-wedge casts here suggests MATs were at least 10°C colder than present during glacial maxima. These data suggest: 1) MATs in this very continental region fluctuated from ~10-12°C or warmer during interglacial maxima to about -6°C or colder during glacial maxima, and 2) “equivalent latitude” shifted at least 8 to 11° southward during interglacial maxima and ~16° northward during glacial maxima. Distribution of Quaternary plant and animal fossils in mid-continental North America and Eurasia records similar and even greater fluctuations of average annual temperatures (at least 16-18°C or 29-32°F).
Rocky Mountain GSA Section Meeting Abstracts with Programs, 2013, Volume 45, No. 5, p. 39.