title: High-Resolution Speleothem-Based Palaeoclimate Records From New Zealand Reveal Robust Teleconnection To North Atlantic During MIS 1-4

authors: Whittaker, Thomas Edward

subjects: New Zealand

abstract: Growth rates, δ18O and δ13C of five stalagmites from the west coasts of North and South Islands, New Zealand, provide records of millennial-scale climate variability over the last ~75 kyr. Thirty-five uranium-series ages were used to provide the chronology. δ18O of stalagmite calcite was influenced by changes in moisture source region, temperature and both δ18O and δ13C primarily display a negative relationship with rainfall. To assist interpretation of climatic signals δ18O profiles were adjusted for the ice-volume effect. Changes in these proxies reflect changes in the strength of the circumpolar westerly circulation and the frequency of southwesterly flow across New Zealand.
MIS 4 was a period of wet and cool climate lasting from 67.7 to 61.3 kyr B.P., expressed in the stalagmites by an interval of strongly negative isotope ratios and increased growth rate. This contrasts with less negative δ18O and δ13C, and slow growth, interpreted as dry and cold climate, during much of MIS 2. This difference between MIS 2 and MIS 4 provides an explanation for why glacial moraines in the Southern Alps of MIS 4 age lie beyond those deposited during the last glacial maximum (MIS 2).
Heinrich events, with the exception of H0 (the Younger Dryas), are interpreted from high-resolution South Island stalagmite HW05-3, from Hollywood Cave, West Coast, as times of wetter and cooler climate. Minima in δ18O and δ13C (wet periods) occurred at 67.7-61.0, 56-55, 50.5-47.5, 40-39, 30.5-29, 25.5-24.3 and 16.1-15. kyr B.P. matching Heinrich events H6-H1 (including H5a) respectively. This demonstrates a robust teleconnection between events in the North Atlantic and New Zealand climate. Minima in δ18O also occurred at similar times in less well-dated North Island stalagmite RK05-3 from Ruakuri Cave, Waitomo.  Speleothems from low-latitudes have revealed that Heinrich events forced southerly displacement of the Intertropical Convergence Zone. This caused steepening of the temperature gradient across mid-southern latitudes, increased westerly circulation and resulted in wet conditions on the west coast of both islands.
Immediately following H1 in the HW05-3 stable isotope profiles is another excursion to more negative isotopic values, suggesting wet and cold climate, lasting from 14.6 to 13.0 kyr B.P. Such a climate on the West Coast at this time has been previously suggested from glacier advance (e.g. Waiho Loop moraine) and decreased abundance of tall trees on the landscape. This event occurred too early to be a response to H0, but is synchronous with a return to cool climate in Antarctica. Thus West Coast climate appears to have been sensitive to changes in Antarctica as well as the North Atlantic.
Isotopic minima (wet and cool climate) in South Island stalagmite GT05-5, which formed during the Holocene, first occurred 4.6 kyr B.P. This began a series of four oscillations in isotope ratios, the last terminating when the stalagmite was collected (2006). Onset of these oscillations is associated with initiation of ice advance in the Southern Alps, and beginning of the Neoglacial. The last oscillation displays enriched isotope ratios lasting from 1.2 to 0.8 kyr B.P. succeeded by depleted ratios lasting until 0.15 kyr B.P., mirroring the Medieval Climate Optimum and Little Ice Age, respectively, of European palaeoclimate records.

text: High-Resolution Speleothem-Based Palaeoclimate Records From New Zealand Reveal Robust Teleconnection To North Atlantic During MIS 1-4 Growth rates, δ18O and δ13C of five stalagmites from the west coasts of North and South Islands, New Zealand, provide records of millennial-scale climate variability over the last ~75 kyr. Thirty-five uranium-series ages were used to provide the chronology. δ18O of stalagmite calcite was influenced by changes in moisture source region, temperature and both δ18O and δ13C primarily display a negative relationship with rainfall. To assist interpretation of climatic signals δ18O profiles were adjusted for the ice-volume effect. Changes in these proxies reflect changes in the strength of the circumpolar westerly circulation and the frequency of southwesterly flow across New Zealand.
MIS 4 was a period of wet and cool climate lasting from 67.7 to 61.3 kyr B.P., expressed in the stalagmites by an interval of strongly negative isotope ratios and increased growth rate. This contrasts with less negative δ18O and δ13C, and slow growth, interpreted as dry and cold climate, during much of MIS 2. This difference between MIS 2 and MIS 4 provides an explanation for why glacial moraines in the Southern Alps of MIS 4 age lie beyond those deposited during the last glacial maximum (MIS 2).
Heinrich events, with the exception of H0 (the Younger Dryas), are interpreted from high-resolution South Island stalagmite HW05-3, from Hollywood Cave, West Coast, as times of wetter and cooler climate. Minima in δ18O and δ13C (wet periods) occurred at 67.7-61.0, 56-55, 50.5-47.5, 40-39, 30.5-29, 25.5-24.3 and 16.1-15. kyr B.P. matching Heinrich events H6-H1 (including H5a) respectively. This demonstrates a robust teleconnection between events in the North Atlantic and New Zealand climate. Minima in δ18O also occurred at similar times in less well-dated North Island stalagmite RK05-3 from Ruakuri Cave, Waitomo.  Speleothems from low-latitudes have revealed that Heinrich events forced southerly displacement of the Intertropical Convergence Zone. This caused steepening of the temperature gradient across mid-southern latitudes, increased westerly circulation and resulted in wet conditions on the west coast of both islands.
Immediately following H1 in the HW05-3 stable isotope profiles is another excursion to more negative isotopic values, suggesting wet and cold climate, lasting from 14.6 to 13.0 kyr B.P. Such a climate on the West Coast at this time has been previously suggested from glacier advance (e.g. Waiho Loop moraine) and decreased abundance of tall trees on the landscape. This event occurred too early to be a response to H0, but is synchronous with a return to cool climate in Antarctica. Thus West Coast climate appears to have been sensitive to changes in Antarctica as well as the North Atlantic.
Isotopic minima (wet and cool climate) in South Island stalagmite GT05-5, which formed during the Holocene, first occurred 4.6 kyr B.P. This began a series of four oscillations in isotope ratios, the last terminating when the stalagmite was collected (2006). Onset of these oscillations is associated with initiation of ice advance in the Southern Alps, and beginning of the Neoglacial. The last oscillation displays enriched isotope ratios lasting from 1.2 to 0.8 kyr B.P. succeeded by depleted ratios lasting until 0.15 kyr B.P., mirroring the Medieval Climate Optimum and Little Ice Age, respectively, of European palaeoclimate records.

year: 2008

title: William Sharman Crawford (Billy) Nicholl, the prospector who discovered the Martha lode at Waihi: his life, told largely in his own words

authors: Hart, Philip

abstract: Billy Nicholl was that rare miner, one who recorded his life. Born in Ireland, when still a boy he arrived in New Zealand in 1862. After his father died at an early age, he acquired a step-father, whom he disliked, with good reason; and in her later years his mother’s mind would fade.
From 1868, when he was probably aged 14, until shortly before his death, he was a prospector and miner. Excited by the early Thames mining days, he learnt the skills needed to be a successful prospector, and during the 1870s worked with several mates on the Coromandel field, with some success. After briefly participating in the Te Aroha rush of 1880, he saw from the summit of that mountain the outcrops of the Waihi reefs, and turned his attention to that largely unexplored area. Although there was considerable claim and counter-claim about who first explored the area and who first found gold, Nicholl was the first to discover a payable lode, the famous Martha. 
After telling his mates of his discovery, they marked out the line of reef and started to develop several claims. For a time Nicholl was in charge of developing his find, and took a leading part in attempting for form a company to work the ground, succeeding on the third attempt. For a while he operated the first battery. But in time he lost control over his discovery and, far from profiting, lost a large amount of money. After leaving Waihi for Karangahake, he would be forced into bankruptcy in 1884.
His first experience of overseas prospecting was in Fiji, where he found traces of gold but nothing payable. Returning to Waihi, he struggled to earn a living for his young family, taking contracts and owning a small farm to supplement his mining endeavours, notably at Maratoto in the 1890s. During that decade his wife abandoned him and their children, and to make his fortune – and because of the lure of another gold rush – he went to Klondike, where he had many exciting experiences but, being unable to mine there, returned poorer than before.
In Nicholl’s last years he did some farming but his main interest continued to be prospecting, and he explored the Waitekauri area into his eighties until declining health forced him to desist. In his later years he recorded details of his life, notably several versions of the discovery of the Martha lode, to the great benefit of posterity.

text: William Sharman Crawford (Billy) Nicholl, the prospector who discovered the Martha lode at Waihi: his life, told largely in his own words Billy Nicholl was that rare miner, one who recorded his life. Born in Ireland, when still a boy he arrived in New Zealand in 1862. After his father died at an early age, he acquired a step-father, whom he disliked, with good reason; and in her later years his mother’s mind would fade.
From 1868, when he was probably aged 14, until shortly before his death, he was a prospector and miner. Excited by the early Thames mining days, he learnt the skills needed to be a successful prospector, and during the 1870s worked with several mates on the Coromandel field, with some success. After briefly participating in the Te Aroha rush of 1880, he saw from the summit of that mountain the outcrops of the Waihi reefs, and turned his attention to that largely unexplored area. Although there was considerable claim and counter-claim about who first explored the area and who first found gold, Nicholl was the first to discover a payable lode, the famous Martha. 
After telling his mates of his discovery, they marked out the line of reef and started to develop several claims. For a time Nicholl was in charge of developing his find, and took a leading part in attempting for form a company to work the ground, succeeding on the third attempt. For a while he operated the first battery. But in time he lost control over his discovery and, far from profiting, lost a large amount of money. After leaving Waihi for Karangahake, he would be forced into bankruptcy in 1884.
His first experience of overseas prospecting was in Fiji, where he found traces of gold but nothing payable. Returning to Waihi, he struggled to earn a living for his young family, taking contracts and owning a small farm to supplement his mining endeavours, notably at Maratoto in the 1890s. During that decade his wife abandoned him and their children, and to make his fortune – and because of the lure of another gold rush – he went to Klondike, where he had many exciting experiences but, being unable to mine there, returned poorer than before.
In Nicholl’s last years he did some farming but his main interest continued to be prospecting, and he explored the Waitekauri area into his eighties until declining health forced him to desist. In his later years he recorded details of his life, notably several versions of the discovery of the Martha lode, to the great benefit of posterity.

year: 2016

title: Vital evidence: Change in the marine ¹⁴C reservoir around New Zealand (Aotearoa) and implications for the timing of Polynesian settlement.

authors: Petchey, Fiona

abstract: Precise and accurate radiocarbon chronologies are essential to achieve tight chronological control for the ~ 750-years since Polynesian settlement of New Zealand. This goal has, however, been elusive. While radiocarbon datasets in the region are typically dominated by marine and estuarine shell dates, such chronological information has been ignored by those interpreting the timing of key events because a detailed regional calibration methodology for marine shell, comparable to the highly precise Southern Hemisphere calibration curve, is lacking. In this paper, we present the first temporal ¹⁴C marine offset (ΔR) model for New Zealand based on paired estuarine/marine and terrestrial radiocarbon dates from 52 archaeological contexts. Our dataset displays significant offsets between the measured New Zealand data and the modelled global marine radiocarbon curve. These shifts are associated with oceanographic fluctuation at the onset of the Little Ice Age ~ AD 1350-1450 (650-500 BP). The application of a regional and temporal correction to archaeological shell dates provides complimentary information to terrestrial radiocarbon production and has the potential to add structure to the blurred chronology that has plagued archaeological theories about the colonization of New Zealand, and other Pacific islands, for decades.

text: Vital evidence: Change in the marine ¹⁴C reservoir around New Zealand (Aotearoa) and implications for the timing of Polynesian settlement. Precise and accurate radiocarbon chronologies are essential to achieve tight chronological control for the ~ 750-years since Polynesian settlement of New Zealand. This goal has, however, been elusive. While radiocarbon datasets in the region are typically dominated by marine and estuarine shell dates, such chronological information has been ignored by those interpreting the timing of key events because a detailed regional calibration methodology for marine shell, comparable to the highly precise Southern Hemisphere calibration curve, is lacking. In this paper, we present the first temporal ¹⁴C marine offset (ΔR) model for New Zealand based on paired estuarine/marine and terrestrial radiocarbon dates from 52 archaeological contexts. Our dataset displays significant offsets between the measured New Zealand data and the modelled global marine radiocarbon curve. These shifts are associated with oceanographic fluctuation at the onset of the Little Ice Age ~ AD 1350-1450 (650-500 BP). The application of a regional and temporal correction to archaeological shell dates provides complimentary information to terrestrial radiocarbon production and has the potential to add structure to the blurred chronology that has plagued archaeological theories about the colonization of New Zealand, and other Pacific islands, for decades.

year: 2020