A periglacial stratified slope deposit in the valley and ridge province of central Pennsylvania, USA: Sedimentology, stratigraphy, and geomorphic evolution
The sedimentology and stratigraphy of a stratified slope deposit in central Pennsylvania together with existing pollen data and global climate simulations are used to develop a model for stratified slope deposition within the context of a waxing and waning Late Wisconsinan periglacial climate. The d...
Published in: | Permafrost and Periglacial Processes |
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Format: | Article in Journal/Newspaper |
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Online Access: | https://doi.org/10.1002/ppp.3430020208 |
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ftrepec:oai:RePEc:wly:perpro:v:2:y:1991:i:2:p:141-162 2023-05-15T16:37:59+02:00 A periglacial stratified slope deposit in the valley and ridge province of central Pennsylvania, USA: Sedimentology, stratigraphy, and geomorphic evolution Thomas W. Gardner John B. Ritter Christopher A. Shuman James C. Bell Kathryn C. Sasowsky Nicholas Pinter https://doi.org/10.1002/ppp.3430020208 unknown https://doi.org/10.1002/ppp.3430020208 article ftrepec https://doi.org/10.1002/ppp.3430020208 2020-12-04T13:31:03Z The sedimentology and stratigraphy of a stratified slope deposit in central Pennsylvania together with existing pollen data and global climate simulations are used to develop a model for stratified slope deposition within the context of a waxing and waning Late Wisconsinan periglacial climate. The deposit consists of well‐stratified beds of platy, subangular shale chips ranging in size from very fine to very coarse gravel and is characterized by two facies: a matrix‐supported facies and a clast‐supported facies. Mechanical breakdown of bare, highly fractured shale bedrock by frost shattering and freeze‐thaw activity in a periglacial environment in front of the Late Wisconsinan glacial boundary provided an abundant and continuous sediment supply. Gelifracts were transported from bedrock source areas to depositional sites along valley side‐slopes by sheetwash and debris flow processes, creating an inclined (10º), aggradational surface of low relief. Surface runoff was derived from snow melt and rainfall onto impermeable frozen ground and bedrock surfaces. The cyclic nature and timing of deposition indicate that sediment was produced and transported immediately prior to and after the Late Wisconsinan glacial maximum. The Late Wisconsinan glacial maximum was characterized by permafrost conditions with reduced sediment supply and erosional truncation of the stratified slope deposit. Frost cracks, ice wedges and soil wedges developed on an unconformity within the deposit during the glacial maximum. La sédimentologie et la stratigraphie d'un dépôt de pente stratifié du centre de la Pennsylvanie, ainsi que des données palynologiques et des simulations globales du climat ont été considérées pour développer un modèle de formation de dépôts de pente stratifiés dans le contexte du climat périglaciaire de la fin de la dernière glaciation. Le dépôt consiste dans des lits bien stratifiés de débris plats subanguleux de schiste variant en taille, de très fins à très grossiers, et caractérisés par deux facies: un faciés à matrice et un faciès sans matrice. La désagrégation mécanique du bedrock schisteux dénudé par les actions de gel/dégel dans un environnement périglaciaire situé non loin du front glaciaire wisconsinien, a fourni une alimentation abondante et continue en sédiments. Les débris fracturés ont été transportés depuis la roche en place vers les sites de dépôts le long des pentes de la vallée par le ruissellement en nappe et des laves torrentielles, en créant une surface faiblement inclinee (10º) d'accumulation. L'ecoulement en surface provenait de la fonte des neiges et des precipitations sur un sol gele et un bedrock impermeables. La nature cyclique et l'tpoque de depbt indiquent quc les sediments ont ete produits et transportes immediatement avant et apres le maximum glaciaire wisconsinien. Ce maximum glaciaire a ete caracterise par des conditions de pergelisol avec une fourniture reduite en sediments et une periode d'erosion tronquant le depbt de pente stratifie. Des fissures de gel, des coins de glace et des coins de sol sont apparus sur cette discordance pendant le maximum glaciaire. Article in Journal/Newspaper Ice permafrost wedge* RePEc (Research Papers in Economics) Permafrost and Periglacial Processes 2 2 141 162 |
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Open Polar |
collection |
RePEc (Research Papers in Economics) |
op_collection_id |
ftrepec |
language |
unknown |
description |
The sedimentology and stratigraphy of a stratified slope deposit in central Pennsylvania together with existing pollen data and global climate simulations are used to develop a model for stratified slope deposition within the context of a waxing and waning Late Wisconsinan periglacial climate. The deposit consists of well‐stratified beds of platy, subangular shale chips ranging in size from very fine to very coarse gravel and is characterized by two facies: a matrix‐supported facies and a clast‐supported facies. Mechanical breakdown of bare, highly fractured shale bedrock by frost shattering and freeze‐thaw activity in a periglacial environment in front of the Late Wisconsinan glacial boundary provided an abundant and continuous sediment supply. Gelifracts were transported from bedrock source areas to depositional sites along valley side‐slopes by sheetwash and debris flow processes, creating an inclined (10º), aggradational surface of low relief. Surface runoff was derived from snow melt and rainfall onto impermeable frozen ground and bedrock surfaces. The cyclic nature and timing of deposition indicate that sediment was produced and transported immediately prior to and after the Late Wisconsinan glacial maximum. The Late Wisconsinan glacial maximum was characterized by permafrost conditions with reduced sediment supply and erosional truncation of the stratified slope deposit. Frost cracks, ice wedges and soil wedges developed on an unconformity within the deposit during the glacial maximum. La sédimentologie et la stratigraphie d'un dépôt de pente stratifié du centre de la Pennsylvanie, ainsi que des données palynologiques et des simulations globales du climat ont été considérées pour développer un modèle de formation de dépôts de pente stratifiés dans le contexte du climat périglaciaire de la fin de la dernière glaciation. Le dépôt consiste dans des lits bien stratifiés de débris plats subanguleux de schiste variant en taille, de très fins à très grossiers, et caractérisés par deux facies: un faciés à matrice et un faciès sans matrice. La désagrégation mécanique du bedrock schisteux dénudé par les actions de gel/dégel dans un environnement périglaciaire situé non loin du front glaciaire wisconsinien, a fourni une alimentation abondante et continue en sédiments. Les débris fracturés ont été transportés depuis la roche en place vers les sites de dépôts le long des pentes de la vallée par le ruissellement en nappe et des laves torrentielles, en créant une surface faiblement inclinee (10º) d'accumulation. L'ecoulement en surface provenait de la fonte des neiges et des precipitations sur un sol gele et un bedrock impermeables. La nature cyclique et l'tpoque de depbt indiquent quc les sediments ont ete produits et transportes immediatement avant et apres le maximum glaciaire wisconsinien. Ce maximum glaciaire a ete caracterise par des conditions de pergelisol avec une fourniture reduite en sediments et une periode d'erosion tronquant le depbt de pente stratifie. Des fissures de gel, des coins de glace et des coins de sol sont apparus sur cette discordance pendant le maximum glaciaire. |
format |
Article in Journal/Newspaper |
author |
Thomas W. Gardner John B. Ritter Christopher A. Shuman James C. Bell Kathryn C. Sasowsky Nicholas Pinter |
spellingShingle |
Thomas W. Gardner John B. Ritter Christopher A. Shuman James C. Bell Kathryn C. Sasowsky Nicholas Pinter A periglacial stratified slope deposit in the valley and ridge province of central Pennsylvania, USA: Sedimentology, stratigraphy, and geomorphic evolution |
author_facet |
Thomas W. Gardner John B. Ritter Christopher A. Shuman James C. Bell Kathryn C. Sasowsky Nicholas Pinter |
author_sort |
Thomas W. Gardner |
title |
A periglacial stratified slope deposit in the valley and ridge province of central Pennsylvania, USA: Sedimentology, stratigraphy, and geomorphic evolution |
title_short |
A periglacial stratified slope deposit in the valley and ridge province of central Pennsylvania, USA: Sedimentology, stratigraphy, and geomorphic evolution |
title_full |
A periglacial stratified slope deposit in the valley and ridge province of central Pennsylvania, USA: Sedimentology, stratigraphy, and geomorphic evolution |
title_fullStr |
A periglacial stratified slope deposit in the valley and ridge province of central Pennsylvania, USA: Sedimentology, stratigraphy, and geomorphic evolution |
title_full_unstemmed |
A periglacial stratified slope deposit in the valley and ridge province of central Pennsylvania, USA: Sedimentology, stratigraphy, and geomorphic evolution |
title_sort |
periglacial stratified slope deposit in the valley and ridge province of central pennsylvania, usa: sedimentology, stratigraphy, and geomorphic evolution |
url |
https://doi.org/10.1002/ppp.3430020208 |
genre |
Ice permafrost wedge* |
genre_facet |
Ice permafrost wedge* |
op_relation |
https://doi.org/10.1002/ppp.3430020208 |
op_doi |
https://doi.org/10.1002/ppp.3430020208 |
container_title |
Permafrost and Periglacial Processes |
container_volume |
2 |
container_issue |
2 |
container_start_page |
141 |
op_container_end_page |
162 |
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1766028278470017024 |