4 Recent Advances in Soil and Paleosol Science

This session highlights recent research in soil and paleosol science. We invite submissions from field, laboratory, and modeling studies that leverage or examine pedogenic processes and archives from deep-time through modern systems.

Sunday, 19 October 2025
8:00 AM - 12:00 PM
HBGCC, 212AB

REGIONAL VARIABILITY OF PALEOCLIMATIC AND PALEOENVIRONMENTAL SIGNALS PRESERVED ALONG ISOCHRONOUS LANDSCAPES OF THE EOCENE-OLIGOCENE TRANSITION ACROSS THE NORTHERN GREAT PLAINS

Paper number: 4-4
Program: Technical Sessions
Time: 8:50 AM – 9:05 AM

Authors

Abstract

The terrestrial record of the Eocene-Oligocene Transition (EOT) on the Northern Great Plains is interpreted as a shift from hothouse to icehouse conditions based on changes in sedimentology, paleopedology, and vertebrate paleontology.  Newly acquired radiometric dates of airfall tuff deposits across the northern Great Plains (the White River Sequence of WY, NE and SD) allows for a refinement of the timing of regional changes across this transition. Changes in sedimentology are preserved as up-section transitions from fluvial-dominated to eolian-dominated deposits.  Specifically, channel facies change up-section from meandering to flashy morphologies and pedogenic modification of floodplain deposits change from well-developed profiles with distinct horizonation to progressively less-developed profiles that eventually form in eolian deposits that shift between periods of aggradation and geomorphic stability.  Indicators of paleoclimatic and paleoenvironmental change from the vertebrate record include the loss of large browsers and crocodylomorphs across the EOT in deposits from NE and SD, up-section changes in stable isotope values of skeletal material in NE, and the general up-section change in vertebrate assemblages (NALMA zones) in NE and SD.  While these up-section changes in sedimentology and vertebrate records are generally consistent at individual locations across the region, lateral changes along isochronous landscapes and within distinct, geochronologically controlled intervals are not. Paleosols change from thin, weakly developed profiles in WY to thicker, well-developed profiles in NE. Eolian-dominated deposits of WY are temporally equivalent with fluvial, mudstone-dominated sections in NE. Isotopic values of vertebrate materials shift toward progressively wetter and cooler conditions from WY to NE, and the Middle Chadronian NALMA is diachronous by ~100ky from WY to NE.  The degree to which these patterns are responding to local, regional, or global drivers is unknown at this time.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414262

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.