Topographically-controlled Deglacial History of the Humber River Basin, Western Newfoundland

Abstract

<jats:title>Abstract</jats:title><jats:p>The Humber River in western Newfoundland flows through a large interior basin, that influenced Late Wisconsinan ice flow from major dispersal centres to the north, in the Long Range Mountains, and to the east in The Topsails. An early southward ice flow from a source to the north covered coastal areas in the western part of the basin. Subsequent regional ice flow was southwestward to northwestward from The Topsails, while south to southwestward flowing ice from the Long Range Mountains occupied the upper Humber River valley. This flow was confluent with ice from The Topsails and moved northwestward toward Bonne Bay. Regional deglaciation began about 13 ka from the inner coast. Ice occupying the Deer Lake valley dammed glacial Lake Howley in the adjacent Grand Lake and Sandy Lake basins to an elevation up to 85 m above present lake levels, which were controlled by drainage through a western outlet feeding into St. George’s Bay. The lake was lowered by exposure of the South Brook valley outlet, and finally drained catastrophically through a spillway at Junction Brook. Marine limit at the coast was 60 m asl. Inland deltas at the head of Deer Lake and fine-grained sediment exposed in the Deer Lake valley show inundation below 45 m present elevation. This produced a narrow embayment extending at least 50 km inland from the modern coast and is named here as ‘Jukes Arm’. Dated marine macrofossils in the Humber Arm and lower Humber River valley, indicate the deltas at the head of Deer Lake formed about 12.5 ka.</jats:p>

Contemporary effective population and metapopulation size (Ne and meta‐Ne): comparison among three salmonids inhabiting a fragmented system and differing in gene flow and its asymmetries

“…The focal system consists of seven interconnected lakes or 'ponds' (P1-P7: Fig. 1) in the Upper Humber River, Gros Morne National Park, Newfoundland (details in Gomez-Uchida et al 2009), where Atlantic salmon (Salmo salar), brook trout (Salvelinus fontinalis) and Arctic char (Salvelinus alpinus) naturally co-occur as non-anadromous landlocked populations, probably founded from anadromous populations that survived the Wisconsinan glacial maximum (10,000-12,000 BP) (Batterson and Catto 2001;Shaw et al 2006).…”

Interaction of landscape and life history attributes on genetic diversity, neutral divergence and gene flow in a pristine community of salmonids

“…These results applied to all three species (even though some sample restrictions were evident: see previous section) strongly suggesting founder effects in populations above waterfalls by downstream colonizers following changes in water level and/or isostatic rebound during deglaciation in Gros Morne National Park c . 12 000 years bp (Batterson & Catto 2001). Such colonization pattern has been suggested for S. fontinalis inhabiting lowland and highland areas in the Park (Poissant et al.…”

Late Quaternary Relative Sea-Level Change on the West Coast of Newfoundland*

“…RSL curves from Pinware, southern Labrador (Clark and Fitzhugh, 1992), Strait of Belle Isle (Grant, 1992), Port au Choix and Bellburns (this study) are examples of the former, whereas those from Bay of Islands (Batterson and Catto, 2001) and St. George's Bay (Bell et al, 2003) are examples of the latter (Fig. 1C).…”

“…We choose 4 RSL curves to represent the full range of postglacial emergence along the west coast of Newfoundland: Port au Choix and Bellburns curves (this study) representing continuous emergence records from the Northern Peninsula; and Bay of Islands and St. George's Bay curves (Batterson and Catto, 2001;Bell et al, 2003) representing "J-shaped" curves from the southwest. In the case of the Bay of Islands curve, we calibrated the radiocarbon dates presented by Batterson and Catto (2001) using the approach outlined above and interpolated a best-fit curve according to their published RSL interpretation (Fig. 5A).…”

“…Existing RSL data broadly confirm the modelled pattern, although the data mostly consist of emergent features that date to initial establishment of higher sea levels in the late Wisconsinan and early Holocene (~17 000-8500 cal BP), with much less coverage spanning the mid to late Holocene (~8000-2000 cal BP) when sea levels were lower than present (Liverman, 1994;Shaw and Forbes, 1995;Shaw et al, 2002). The west coast of Newfoundland has been the focus of several RSL studies over the last decade or so (Clark and Fitzhugh, 1992;Grant, 1992Grant, , 1994Batterson and Catto, 2001;Daly, 2002;Bell et al, 2003;Smith et al, 2005) such that there is now a sufficient database with which to critically examine the proposed migration of a marginal forebulge. Because of the apparent role of glacioeustasy in the RSL history of southwest Newfoundland, Bell et al (2003) suggested that a broader re-evaluation of the relative roles of glacioisostatic and glacioeustatic components in the postglacial sea-level record of the island was necessary.…”