quaternary Article Late Quaternary Stratigraphy and Geochronology of the Spring Creek Drainage along the Southern High Plains Eastern Escarpment, Northwest Texas Eileen Johnson, Stance Hurst * and John A. Moretti Museum of Texas Tech University, 3301 4th St, Lubbock, TX 79415, USA; [email protected] (E.J.); [email protected] (J.A.M.) * Correspondence: [email protected] Abstract: The eastern escarpment breaks of the Southern High Plains of Texas are both a geomor- phic and ecotonal transition zone from the high plains surface to the Rolling Plains below. The geoarchaeological record on the Southern High Plains surface is well documented, but few studies have investigated the sediments, soils, and geochronology of the eastern escarpment. The current investigation has targeted the discontinuous remnants of Late Quaternary deposits within Spring Creek, a tributary within the upper Brazos River basin. A total of 19 profiles, core, and isolated exposure locations placed along a transect from Macy Fork through upper Spring Creek and 40 ra- diocarbon ages provide a composite sequence and geochronology that also documents the Late Pleistocene to Late Holocene paleoenvironments of this drainage. The resulting record illustrates a series of major changes in sediments and local habitats over the past ~11,550 radiocarbon years (13,469–13,390 calendar years), characterized primarily by reductions in available water and increas- Citation: Johnson, E.; Hurst, S.; ing aridity that peaked during the middle Holocene. This sequence provides significant context Moretti, J.A. Late Quaternary to an expanding record of Late Pleistocene to middle Holocene biota and cultures. Subsequent 14 Stratigraphy and Geochronology of downcutting of the drainage post-6000 C yr B.P. (6988–6744 calendar years) removed large sections the Spring Creek Drainage along the of the depositional sequence. Local topography within Spring Creek drainage greatly impacted the Southern High Plains Eastern preservation of these deposits. The remaining record provides some different insights than those Escarpment, Northwest Texas. available from the Southern High Plains record. Quaternary 2021, 4, 19. https:// doi.org/10.3390/quat4030019 Keywords: Southern High Plains; Texas; escarpment breaks; Late Pleistocene; fluvio-lacustrine Academic Editor: Jef Vandenberghe Received: 10 May 2021 1. Introduction Accepted: 1 June 2021 Published: 22 June 2021 Over the past 11 years, research activities in the uppermost reaches of Spring Creek on the eastern edge of the Southern High Plains, Texas, have identified, explored, and Publisher’s Note: MDPI stays neutral excavated a series of Late Pleistocene vertebrate faunal localities and Holocene archaeo- with regard to jurisdictional claims in logical sites [1–8]. In addition to faunal and cultural studies, the research effort also has published maps and institutional affil- involved intensive investigation of associated Spring Creek depositional patterns. The Late iations. Quaternary sediments provide essential context to the archaeological and paleontological materials they contain and also offer evidence of environmental change and landscape development. The recent integration of the Spring Creek geochronologic and stratigraphic data accumulated in the past decade has produced a comprehensive record of abiotic processes that contributes to understanding the natural history of both this small drainage Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. as well as the broader region. This article is an open access article New and expanded results of the ongoing research program are summarized here. distributed under the terms and These results constitute a small-scale landscape study focused on the eastern escarpment conditions of the Creative Commons breaks of the Southern High Plains. This work represents a building block to understanding Attribution (CC BY) license (https:// the dynamic setting and effects of erosion on the eastern escarpment breaks. This small- creativecommons.org/licenses/by/ scale study also may be applicable elsewhere in mid-latitudes that have experienced strong 4.0/). Quaternary 2021, 4, 19. https://doi.org/10.3390/quat4030019 https://www.mdpi.com/journal/quaternary Quaternary 2021, 4, x FOR PEER REVIEW 2 of 49 Quaternary 2021, 4, 19 2 of 37 small-scale study also may be applicable elsewhere in mid-latitudes that have experienced strong climate shifts during the Late Pleistocene and Holocene coupled with different pe- climateriods of shifts erosion during and sediment the Late Pleistocenedeposition, andparticularly Holocene in coupled areas of withpronounced different topographic periods of erosionrelief. and sediment deposition, particularly in areas of pronounced topographic relief. TheThe SouthernSouthern HighHigh Plains,Plains, oror LlanoLlano Estacado,Estacado, isis anan expanseexpanse ofof short-grassshort-grass steppesteppe inin northwesternnorthwestern TexasTexas and and eastern eastern New New Mexico Mexico (Figure (Figure1). Spring1). Spring Creek Creek is located is located within within the easternthe eastern escarpment escarpment breaks, breaks, the ruggedthe rugged topographic topographic transition transition between between the the level level Southern South- Highern High Plains Plains uplands uplands and and the Rollingthe Rolling Plains Plains below. below. This This distinct distinct geographic geographic subregion subregion or ecotoneor ecotone (e.g., (e.g., [9]) [9]) extends extends for ~450for ~450 km km (~279 (~279 miles) miles) (Figure (Fig1ure) from 1) from north north to south to south along along the easternthe eastern edge. edge. It has It anhas elevational an elevational difference difference of ~300 of m~300 in them in north the north to 100 to m 100 in the m southin the fromsouth the from Southern the Southern High Plains High uplandsPlains uplands to the low-lying to the low plains-lying below. plains This below. subregion This subre- has beengion littlehas been studied little in studied terms of in its terms post-bedrock of its pos Quaternaryt-bedrock Quaternary geological, geological, geomorphological, geomor- orphological, archaeological or archaeological records. records. FigureFigure 1.1. SouthernSouthern HighHigh PlainsPlains withwith itsits regionalregional drainagedrainage system,system, easterneastern escarpmentescarpment ecotoneecotone inin gray,gray, and and locations locations of of the the greater greater Post Post research research area area and and Lubbock Lubbock Lake Lake landmark landmark as noted as noted in the in text. the text. Spring Creek is part of the South Fork of the Double Mountain Fork of the Brazos River drainageSpring and Creek lies within is part the of largerthe South Post Fork research of the area Double inside Mountain an extensive Fork historic of the Brazos ranch (FigureRiver drainage2). An initial and overview lies within of thethe sedimentslarger Post and research soils [ 8area] across inside that an larger extensive research historic area (aranch mesoscale (Figure landscape 2). An initial study) overview has pointed of the out: sediments (1) Late and Pleistocene soils [8] across and Early that Holocene larger re- sedimentssearch area and (a mesoscale soils occur landscape in the upper study) tributary has pointed drainages; out: and(1) Late (2) these Pleistocene areas are and targets Early forHolocene future research,sediments particularly and soils occur for locating in the upper in-situ tributary archaeological drainages; sites. and (2) these areas are targets for future research, particularly for locating in-situ archaeological sites. Quaternary 2021, 4, 19 3 of 37 Quaternary 2021, 4, x FOR PEER REVIEW 3 of 49 FigureFigure 2. Spring 2. Spring Creek Creek research research area area in in thethe SouthernSouthern High High Plains Plains eastern eastern escarpment escarpment ecotone. ecotone. TheThe research research reported reported here expands the the initial initial work work in upper in upper Spring Spring Creek Creek (e.g., (e.g.,[1,8]) [1,8]) basedbased on on additional additional profiles, profiles, stratigraphic stratigraphic refinement, refinement, and and an an increased increased number number of of radiocarbon radio- carbon dates. Of the 19 localities in Conley [1] and Conley et al. [2], only one (Macy Local- dates. Of the 19 localities in Conley [1] and Conley et al. [2], only one (Macy Locality 10) is ity 10) is within the Spring Creek Valley. The previous study of that one profile has iden- within the Spring Creek Valley. The previous study of that one profile has identified a buried tified a buried soil and provided a radiocarbon date from the A-horizon of the buried soil. soilOf and the provided 17 localities a radiocarbon in Murphy et date al. [8], from only the one A-horizon (Macy Locality of the buried 100) is soil.within Of the the Spring 17 localities in MurphyCreek Valley. et al. Of [8], the only one one profile (Macy previously Locality studied 100) is withinfor Macy the Locality Spring Creek100, the Valley. broad Ofdep- the one profileositional previously units then studied defined for have Macy been Locality refined 100, (e.g., the current broad units depositional 2 and 5 not units previously then defined haveidentified) been refined and the (e.g., depositional current units mode 2 revised. and 5 not Of previously the four radiocarbon identified) dates and then the depositionalavaila- modeble for revised. Macy OfLocality the four 100, radiocarbon additional dates dates indicate then available