Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements

Abstract

Urbanism in the Bronze-age Indus Civilisation (~4.6–3.9 thousand years before the present, ka) has been linked to water resources provided by large Himalayan river systems, although the largest concentrations of urban-scale Indus settlements are located far from extant Himalayan rivers. Here we analyse the sedimentary architecture, chronology and provenance of a major palaeochannel associated with many of these settlements. We show that the palaeochannel is a former course of the Sutlej River, the third largest of the present-day Himalayan rivers. Using optically stimulated luminescence dating of sand grains, we demonstrate that flow of the Sutlej in this course terminated considerably earlier than Indus occupation, with diversion to its present course complete shortly after ~8 ka. Indus urban settlements thus developed along an abandoned river valley rather than an active Himalayan river. Confinement of the Sutlej to its present incised course after ~8 ka likely reduced its propensity to re-route frequently thus enabling long-term stability for Indus settlements sited along the relict palaeochannel.

Neoglacial climate anomalies and the Harappan metamorphosis

“…Compared to settlements along the Indus and its tributaries that can be affected by fluvial erosion , the distribution of archaeological sites on G-H, where large laterally incising Himalayan rivers were absent during the Holocene, is probably more complete and representative of their original distribution. To observe trends related to partial or complete drying of the G-H system Giosan et al, 2012;Singh et al, 2017), we divided the settlements into upper and lower G-H sites located in the modern regions of Punjab and Haryana in India, and Cholistan in Pakistan, respectively. For archaeological site locations and their radiocarbon and/or archaeological ages we follow Giosan et al (2012), using data from the compilation by Gangal et al (2010) with additions from regional gazetteers and surveys (Kumar, 2009;Mallah, 2010;Mughal, 1996Mughal, , 1997Possehl, 1999;Wright et al, 2005).…”

“…The climatic trigger for the urban Harappan collapse was probably the decline of the summer monsoon (e.g., Dixit et al, 2014;Kathayat et al, 2017;MacDonald, 2011;Singh et al, 1971;Staubwasser et al, 2003;Stein, 1931) that led to less extensive and more erratic floods, making inundation agriculture less sustainable along the Indus and its tributaries and may have led to bio-socioeconomic stress and disruptions (e.g., Meadow, 1991;Schug et al, 2013). Still, the remarkable longevity of the decentralized rural phase until ca.…”

Synthesis of Enantioenriched Vicinal Tertiary and Quaternary Carbon Stereogenic Centers within an Acyclic Chain

“…Thea bility of the palladium to isomerize along the carbon chain while preserving the inherent stereochemistry enabled adiastereoretentive ring-opening event suggesting that the Pd does not disengage during the process and migrates on the same stereoface (Scheme 24). [45] This Pd-catalyzed unfolding of the strained cycle remarkably proved its efficiency and versatility,a st he reaction proceeded regardless of the molecular distance between the initiation (double bond) and termination (alcohol) sites (Scheme 24).…”

Synthese enantiomerenangereicherter, vicinaler tertiärer und quartärer Kohlenstoff‐Stereozentren innerhalb einer acyclischen Kette

“…[44] In einem ersten Schritt fand eine Heckartige Carbopalladierung statt, die eine nachfolgende Pd-Wanderung durch schrittweise Additions-Eliminierungs-Reaktionen entlang der Kohlenwasserstoffkette auslçste.D ie Direktionalitätd er Wanderung wird durch die selektive Ringçffnung des Cyclopropylrings getrieben und ist infolge der Transformation der terminalen Hydroxy-in eine Carbonylgruppe katalytisch produktiv.D ie Fähigkeit des Palladiums zur Isomerisierung entlang der Kohlenstoffkette bei gleichzeitiger Beibehaltung der inhärenten Konfiguration ermçglichte ein diastereoretentives Ringçffnungsereignis, was darauf schließen lässt, dass das Pd-Atom während des Prozesses nicht abgespalten wird, sondern entlang derselben Seite wandert (Schema 24). [45] Dieser Pd-katalysierte Öffnungsprozess des gespannten Cyclus belegte eindrucksvoll seine Effizienz und Vielseitigkeit, da die Reaktion unabhängig von den Abständen zwischen den Initiierungs-(Doppelbindung) und Te rminierungsstellen (Alkohol) ablief (Schema 24).…”