Origin and age of The Hillocks and implications for post‐glacial landscape development in the upper Lake Wakatipu catchment, New Zealand

McColl, Samuel T.; Cook, Simon J.; Stahl, Timothy; Davies, Tim

doi:10.1002/jqs.3168

Cited by 4 publications

(2 citation statements)

References 37 publications

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“…erosional escarpments, alluvial channels/plains between topographic highs) indicating that the continuous, bouldery ridges are primary, constructional features. Such organisation is consistent with that expected from lateral moraines and inconsistent with products of landslides which tend to be distributed more chaotically (McColl et al, 2019). Furthermore, the topographic situation of the landform does not support a mass movement origin.…”

Section: Resultssupporting

confidence: 64%

Local summer insolation and greenhouse gas forcing drove warming and glacier retreat in New Zealand during the Holocene

Dowling

Eaves

Norton

et al. 2021

Quaternary Science Reviews

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Geological climate archives from the Holocene Epoch provide baseline information concerning natural climate variability. Temperate mountain glacier extent is sensitive to summer air temperature, thus geological records of past glacier length changes are a useful proxy for this climatic variable. Here we present a new cosmogenic 10 Be chronology of glacier length changes at Dart Glacier in the Southern Alps, New Zealand. Prominent moraines deposited 321 ± 44 yr ago (n ¼ 11) and 7.8 ± 0.3 ka (n ¼ 5) show glaciers during the Little Ice Age were less extensive than during the early Holocene. This pattern of net Holocene glacier retreat is consistent with emerging data from other catchments in New Zealand and across the southern mid-latitudes. Using the physical framework of a transient global climate model simulation, we suggest that cool summers in the early Holocene were promoted by the local summer insolation minimum, together with low atmospheric greenhouse gas concentrations, causing an early Holocene austral glacial maximum. An insolation-driven reduction in seasonality at southern midlatitudes may reconcile differences between early Holocene temperature reconstructions where climate proxies have different seasonal sensitivities. We suggest that rising greenhouse gas concentrations after 7 ka caused regional-scale glacier retreat and appear to be the dominant driver of multimillennial summer temperature trends in the southern mid-latitudes during the present interglacial.

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Section: Resultssupporting

confidence: 64%

Local summer insolation and greenhouse gas forcing drove warming and glacier retreat in New Zealand during the Holocene

Dowling

Eaves

Norton

et al. 2021

Quaternary Science Reviews

View full text Add to dashboard Cite

show abstract

“…Its preservation is likely partly owed to the very sizeable nature of the deposit -having a volume of 27 km 3 . All other pre-historic dated, disrupted RSFs and rock avalanche deposits in the New Zealand Southern Alps are of Holocene age (Bainbridge, 2017), with only four of those occurring in the Early Holocene (Whitehouse and Griffiths, 1983;Lee et al, 2009), and 13 within the Mid-Holocene (Whitehouse and Griffiths, 1983;Hancox et al, 2013;Sweeney et al, 2013;McColl et al, 2019). Another 50 or so are dated from the Late-Holocene with increasing apparent frequency, and more than 100 historically recorded events have occurred since the 1800s (Bainbridge, 2017).…”

Section: Implications For Rock Avalanche Inventoriesmentioning

confidence: 99%

The Anomalously Old Bush Stream Rock Avalanche and Its Implications for Landslide Inventories in Dynamic Landscapes

McColl

2020

Front. Earth Sci.

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Previous dating of rock slope failures in most glaciated mountain chains has revealed almost exclusively young, mostly Holocene ages. In this study, a rock avalanche in the glaciated Rangitata Basin in Canterbury, New Zealand is mapped, described, and dated, revealing a pre-Holocene age of failure. The geomorphology and characteristics of the rock avalanche, named here as the Bush Stream Rock Avalanche, were assessed from field mapping and photogrammetric analyses. To assess the age of the rock avalanche, in situ cosmogenic 10 Be exposure dating was applied to boulders on the deposit. The geomorphological mapping shows that the morphology of the head scarp and deposit of the rock avalanche are distinct from the surrounding landscape, much of which appears to be glacial in origin. The rock avalanche traveled about 4 km, with a volume of 50-100 M m 3 , and appears to have temporarily blocked Bush Stream. The dated boulders suggest an age of >16 ka (and likely >20 ka), making it the oldest reported alpine rock avalanche in New Zealand, and one of the oldest last-glaciation rock avalanches to be reported worldwide. Deep depressions, possibly kettle holes, in the deposit are indicative of runout over a glacier (or associated dead ice), but any glacier present at the time must have been small and probably decaying. The excellent preservation was likely favored by a small catchment located on the dry lee side of the Two Thumb Range which dampened glacial and fluvial activity. The study confirms that rock avalanches were being produced in the Southern Alps early in the last glaciation or early period of deglaciation, but that evidence for them likely exists only in the rare environments that have conditions favorable for preservation. Preservation potential in most of the Southern Alps is low, with older deposits readily buried or eroded by New Zealand's high rates of erosion, aggradation, and dynamic processes. Unless methods can be developed to identify missing older events, we are hampered in our ability to understand the frequency, and therefore causes, of large slope failures in the Southern Alps and in other highly dynamic alpine landscapes.

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The role of liquid water in recent surface processes on Mars

Conway

Stillman

2021

Mars Geological Enigmas

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Origin and age of The Hillocks and implications for post‐glacial landscape development in the upper Lake Wakatipu catchment, New Zealand

Abstract: This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Cited by 4 publications

References 37 publications

Local summer insolation and greenhouse gas forcing drove warming and glacier retreat in New Zealand during the Holocene

Local summer insolation and greenhouse gas forcing drove warming and glacier retreat in New Zealand during the Holocene

The Anomalously Old Bush Stream Rock Avalanche and Its Implications for Landslide Inventories in Dynamic Landscapes

The role of liquid water in recent surface processes on Mars

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