Supplementary material to "A multi-proxy assessment of terrace formation in the lower Trinity River valley, Texas"

Author(s):  
Hima J. Hassenruck-Gudipati ◽  
Thaddeus S. Ellis ◽  
Timothy A. Goudge ◽  
David Mohrig
2021 ◽  
pp. SP523-2021-57
Author(s):  
Rebecca J. Dorsey ◽  
Juan Carlos Braga ◽  
Kevin Gardner ◽  
Kristin McDougall ◽  
Brennan O'Connell

AbstractMarine straits and seaways are known to host a wide range of sedimentary processes and products, but the role of marine connections in the development of large river systems remains little studied. This study explores a hypothesis that shallow marine waters flooded the lower Colorado River valley at ∼ 5 Ma along a fault-controlled former tidal straight, soon after the river was first integrated to the northern Gulf of California. The upper bioclastic member of the southern Bouse Formation provides a critical test of this hypothesis. The upper bioclastic member contains wave ripple-laminated bioclastic grainstone with minor red mudstone, pebbly grainstone with HCS-like stratification and symmetrical gravelly ripples, and calcareous-matrix conglomerate. Fossils include upward-branching segmented coralline-like red algae with no known modern relatives but confirmed as marine calcareous algae, echinoid spines, barnacles, shallow marine foraminifers, clams, and serpulid worm tubes. These results provide evidence for deposition in a shallow marine bay or estuary seaward of the transgressive backstepping Colorado River delta. Tsunamis generated by seismic and meteorologic sources likely produced the HCS-like and wave-ripple cross-bedding in poorly-sorted gravelly grainstone. Marine waters inundated a former tidal strait within a fault-bounded tectonic lowland that connected the lower Colorado River to the Gulf of California. Delta backstepping and transgression resulted from a decrease in sediment output due to sediment trapping in upstream basins and relative sea-level rise produced by regional tectonic subsidence.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5740426


2021 ◽  
Author(s):  
Hima J. Hassenruck-Gudipati ◽  
Thaddeus S. Ellis ◽  
Timothy A. Goudge ◽  
David Mohrig

Abstract. A proposed null hypothesis for fluvial terrace formation is that internally generated or autogenic processes such as lateral migration and river-bend cutoff produce variabilities in channel incision that lead to the abandonment of floodplain segments as terraces. Alternatively, fluvial terraces have the potential to record past environmental changes from external forcings that include temporal changes in sea-level and hydroclimate. Terraces in the Trinity River valley have been previously characterized as Deweyville groups and interpreted to record episodic cut and fill during late Pleistocene sea-level variations. Our study uses high-resolution topography of a bare-earth digital elevation model derived from airborne lidar surveys along ~88 linear km of the modern river valley. We measure both differences in terrace elevations and widths of paleo-channels preserved on these terraces in order to have two independent constraints on terrace formation mechanisms. For 52 distinct terraces, we quantify whether there is a clustering of terrace elevations – expected for allogenic terrace formation tied to punctuated sea-level and/or hydroclimate change – by comparing variability in a chosen set of terrace elevations against variability associated with randomly selected terrace sets. Results show Deweyville groups record an initial valley floor abandoning driven by allogenic forcing, which transitions into autogenic forcing for the formation of younger terraces. For 79 paleo-channel segments preserved on these terraces, we connected observed changes in paleo-channel widths to estimates for river paleo-hydrology over time. Our measurements suggest the discharge of the Trinity River has changed systematically by a factor of ~2 during the late Pleistocene. Methods introduced here combine river-reach scale observations of terrace sets and paleohydrology with local observations of adjacent terrace-elevation change and paleo-channel bend number to show how interpretations of allogenic versus autogenic terrace formation can be evaluated within a single river system.


The Jewett Mine is a ca. 21, 000-acre lignite mine in the post oak savannah of Freestone, Leon, and Limestone counties, Texas. The project area straddles the divide between the Navasota River valley on the west and the Trinity River valley on the east and lies at the western margin of the Caddoan area . Although residential use of the area by the Caddo has not been documented, many sites have yielded small quantities of Caddoan pottery, and it is likely that cultures indigenous to the region were affected by the development of Caddoan culture not far to the east. For reference, the George C. Davis Site (41CE19) lies only 95 km to the east-northeast. In addition to contributing information about the interaction between Caddoan and neighboring groups in the central part of East Texas, the Jewett Mine sites, by virtue of their location in the Eastern Woodlands but outside of the Caddoan area proper, have the potential to shed light on such topics as regional Caddoan settlement systems and the origins of Caddo culture.


1997 ◽  
Vol 16 (1) ◽  
pp. 133-134
Author(s):  
Joanne M. Westphal
Keyword(s):  

2016 ◽  
Vol 27 (3-4) ◽  
pp. 47-54
Author(s):  
K. K. Holoborodko ◽  
V. O. Makhina ◽  
K. S. Buchnieva ◽  
O. E. Pakhomov

Floodplain valley of the Dnieper river midstream is a unique natural complex, having a great bìogeographical, ecological, environmental, historical and recreational values. In 1990, the Natural reserve «Dniprovsko-Orilsky» was established within the area. The Natural reserve «Dniprovsko-Orilsky» is environmentally protected site within the Dnipropetrovsk region, Dnipropetrovsk oblast, Ukraine. This reserve occupies part of the Dnieper river valley and marshy and reedy banks of Protovch river (existing bed of Oril river). It was created by Regulation of the Council of Ministers of the USSR of 15 September 1990, No. 262, based on common zoological and ornitological Nature reserves «Taromskì plavni» and «Obukhovskie zaplavy». On the territory of the Natural reserve «Dniprovsko-Orilsky», they were registered 32 Lepidoptera species listed in the List of Threatened Species at different categories (5 species in IUCN Red List ; 18 in Red Data Book of Ukraine; 7 in European Red List of plants and animals endangered on a global scale; 31 in Red Book of Dnipropetrovsk oblast). The main scientific materials were author’s collections from area of research and materials of entomological funds, Department of Zoology and Ecology, Oles Honchar Dnipropetrovsk National University (mostly Memorial Collection of V. O. Barsov). Field surveys covered all the ecosystems basic on size and degree of protection. The author’s researches have conducted over the past decade during annual expeditions to the Reserve. Taxonomic structure of the complex is quite diverse, and represented by all the major families of higher millers and rhopalocera, having protectedstatus. In relation to taxonomy, this complex formed by representatives of five superfamilies (Zyganoidea, Noctuoidea, Bombycoidea, Hesperioidea, Papilionoidea) from 11 families (Zygaenidae, Saturniidae, Sphingidae, Noctuidae Arctiidae Hesperiidae, Papilionidae, Pieridae, Nymphalidae, Satyridae, Lycaenidae). High taxonomic diversity can be explained by unique geographical location of the reserve in azonal conditions of the Dnieper river valley. Such location allows to enter different zoogeographic Lepidoptera groups on the reserve territory. Zoogeographic analysis of species protected within the reserve territory selected 7 basic groups. It was found that most of the globally rare species have Mediterranean origin (39 %); species of Palearctic origin are in second place (22 %); Western Palearctic and Ponto-Kazakh types of areas are same of number of species, and come third (11 %); and others come 17 % (European, Euro-Siberian, and Holarctic). This fauna component is specific due to presence of so-called «northern» species that make up 40 % (representatives of Palearctic, Western Palearctic, Euro-Siberian, European and Holarctic groups). Their existence within the reserve territory is only possible due to development of boreal valley ecosystems. High taxonomic diversity can be explained by unique geographical location of the reserve in azonal conditions of the Dnieper river valley. Such location allows to enter different zoogeographic Lepidoptera groups on the reserve territory. Zoogeographic analysis of species protected within the reserve territory selected 7 basic groups. It was found that most of the globally rare species have Mediterranean origin (39 %); species of Palearctic origin are in second place (22 %); Western Palearctic and Ponto-Kazakh types of areas are same of number of species, and come third (11 %); and others come 17 % (European, Euro-Siberian, and Holarctic). This fauna component is specific due to presence of so-called «northern» species that make up 40 % (representatives of Palearctic, Western Palearctic, Euro-Siberian, European and Holarctic groups). Their existence within the reserve territory is only possible due to development of boreal valley ecosystems.


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