G. Leslie Adkin (1888–1964) and glaciation of the Tararua Range,North Island,New Zealand

I Introduction

Leslie Adkin was born in Wellington, New Zealand, on 26 July 1888. Leslie Adkin’s family were keen naturalists, and purchased a hundred acres of land on the Horowhenua coastal plain near Levin, to the north of Wellington (Figure 1). This area is to the west of the Tararua Range, part of the axial ranges of the North Island (Williams, 2004). As books such as Marr (1890), Roberts (1893), Hochstetter (1863), Geikie (1902) and, importantly, James Park’s Geology of New Zealand (1910), along with Transactions of the New Zealand Institute, were kept within the house, Adkin had a range of sources to satisfy his appetite for geoscience. During two years as a boarder at Wellington College in 1903–1904, Adkin developed an enthusiasm for collecting plants and rocks and learned to process his own photographs. When Adkin returned to work on the family farm he began a diary, which he kept to within a month of his death. It was an account of farm, community and family life, and it is also a record of his field studies and scientific observations (Dreaver, 1997). In addition to his daily diary and published work in scientific journals, Adkin also assembled a collection of geological notebooks that recorded his field observations, focused on the landforms of the lower North Island of New Zealand. The aim of this paper is to outline Adkin’s background and career, and to describe his contribution to New Zealand geoscience, one of the highlights being his (at the time controversial) evidence for a limited glaciation of New Zealand during the Pleistocene (Adkin, 1911a). This was against the prevailing theory of that time, put forward by Professor James Park during the early 20th century (Park, 1909a, 1909b, 1909c).

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Figure 1

Location of Park Valley in the Tararua Range, North Island, New Zealand.

II Adkin the geoscientist

Adkin’s first published work was concerned with the relationship between the Tararua Range and the adjacent Horowhenua coastal plain (Adkin, 1911b), having observed spatial variations in sedimentology while sinking post-holes across farmland. In this work, Adkin (1911b) analysed alluvial fan development under oscillating climate and sea levels along the range-front, studying artesian bore reports from the Weraroa State Farm, before formulating a hypothesis about the area’s long-term geomorphic development (Adkin, 1911b). Adkin concluded that the Ohau River, 4 km south of Levin (Figure 1), had once flowed further north, and he compared his hypothesis with Speight’s (1907) findings from the South Island’s Canterbury plains: ‘the Ohau … has raised its bed in much the same manner as the Waimakariri River has done’ (Adkin, 1911b: 518). On 3 October 1910, the Wellington Philosophical Society summoned Adkin to present this theory at their meeting two days later, and the paper was published soon after (Adkin, 1911a). Thus, Adkin, farmer, amateur scientist, archaeologist and photographer, had a geomorphological paper published before his more illustrious (professional) counterpart, Charles Cotton, Lecturer in Geology at Victoria College (see Cotton, 1912). Although Adkin was a competent cartographer, his detailed maps and two-dimensional drawings can best be described as functional (see, for example, Figure 2A), when compared with the more artistic three-dimensional landform sketches of Cotton (1945).

III Glaciation of the Tararua Range

In 1909, although some of the highest Tararua peaks were mapped (Mitre at 1571 m is the highest), no one had traversed the range. In February 1909, Adkin commenced the first successful traverse, from Levin to Masterton (Figure 1). The Horowhenua Māori, the Muaupoko, had spoken of a ‘lost-lake’ within the range, and Adkin hypothesized that if this lake indeed existed it could be a moraine-dammed proglacial lake. Adkin’s equipment was heavy and cumbersome, including canvas tent, tweed clothing, Abney level, compass, barometer, notebook and glass plates for his camera. Reaching Arete Peak at the head of Park Valley (Figure 1), it was the topography of the valley to the southwest (Figure 2) that most excited Adkin:

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Figure 2

(A) Adkin’s (1911a) sketch of the upper part of Park Valley, and the three ‘hanging valleys' (Mt Dora was later renamed Pukematawai). (B) Self-portrait of Adkin (September 1913), taken on his farm at Levin looking east (source: George L. Adkin/Museum of New Zealand Te Papa Tongarewa (A.005940). (C) The broad, U-shaped Park Valley, Tararua Range, taken from the southern slopes of Arete.

The topography of the upper portions of this valley is undoubtedly of glacial origins. The head of the valley, which is U-shaped is a glacial cirque – the bounding precipices of which were preserved on SW face of Arete Peak, half-way up. The continuity of the precipices is broken by 3 large U-shaped hanging valleys. The largest of these lies on the south side of Arete Peak and has a small cirque at its head. (Adkin Diary, 12 March 1911)

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Figure 3

(A) The easternmost ‘hanging valley’ identified by Adkin. (B) The two western ‘hanging valleys', separated by the ridge Adkin camped on in 1911. Subsequent sedimentological work by Brook and Crow (2008) identified this as a moraine ridge.

The lip of each of these U-shaped hanging valleys has been deeply cut by gorge … formed by recent stream action … Further down the valley, the debris on its floor has been cut to a depth of up to 20ft by the stream which drains the valley. (Adkin Diary, 12 March 1911)

James Park had taught Charles Cotton at Otago University, and had recently claimed evidence for glaciation in Wellington Harbour/Port Nicholson (Park, 1909a), Cook Strait between the North and South Islands (Park, 1909b) and the Rangitikei area ~120 km north of Levin (Park, 1909c). Patrick Marshall (1909), a less renowned contemporary of Park, had a contrasting idea to Park, that the North Island had been subjected to very little glacial activity during the Pleistocene. Park’s (1909a, 1909b, 1909c) hypothesis was that New Zealand had once been all but submerged beneath a large ice sheet that had extended north from Antarctica, and Adkin’s ideas now indicated that the North Island had been subjected to a much more limited alpine-style glaciation, and this finding would later settle the Park-Marshall argument. Returning home after his second Tararua Range expedition, Adkin worked in his spare time (evenings and Sundays) on a paper focused on glaciation and long-term evolution of the Tararua Range. The Wellington Philosophical Society asked him to present findings at their September meeting, in the middle of the lambing season. Adkin had much to prepare, challenging accepted wisdom, namely about glaciation, and that the drainage patterns were caused by ‘adjustment to structure’. This idea was that rocks were uplifted, formed a peneplain, and were then split by longitudinal faults, forming alternate bands of resistant and weak rocks, the weaker bands being incised into valleys (Cotton, 1945). Adkin’s ‘anticlinorium theory’ was more complex, concluding the range formed by west–east compression in the crust, up-warping the range as an anticline, with the Wairarapa Fault on the eastern margin of the range evidence of this compression (Adkin Diary, 6 September 1911).

Adkin presented his theories on 6 September 1911 (entitled ‘Accounts of some aspects of glaciation in the Tararua Ranges'), though reaction was varied. At the meeting, Charles Cotton of Victoria University College concluded that Adkin’s evidence of alpine-style glaciation was inconclusive and that Adkin’s photographs did not show glacial features. Cotton also stated that there had been one period of folding in the Jurassic and none since, so Adkin’s anticlinorium hypothesis was unlikely as there had been ‘insufficient time for base levelling several times over’ (Adkin Diary, 6 September 1911). Clearly, (the academic) Cotton did not think (the amateur) Adkin’s ideas were convincing. Government palaeontologist J.M. Thompson thought ‘the supposed glacial topography was more likely due to stream erosion so the evidence of the former was inadequate as there was no striae, roche moutonees or moraines' (Adkin Diary, 6 September 1911). Furthermore, Adkin logged in his diary (6 September 1911) that George Hogben, an eminent seismologist, was ‘against the Wairarapa fault as a factor in my anticlinorium hypothesis'. Nevertheless, Adkin did gain support from P.G. Morgan, the Director of the New Zealand Geological Survey, who ‘considered my case as regards former glaciation and generally backed me up’ (Adkin Diary, 6 September 1911). It must have been disconcerting for Adkin, the farmer and keen amateur geologist, to present radical findings to the cream of Wellington’s scientific community at the time, and the meeting was the first of several clashes over the years between Adkin and Cotton on the geomorphology of the lower North Island. Adkin’s paper was eventually published, focusing only on glaciation (Adkin, 1911b), with Adkin’s ‘anticlinorium’ theory later submitted to Transactions of the New Zealand Institute, but was rejected due to ‘ideas based on too slender evidence and in part, erroneous' (Adkin Diary, 10 March 1913).

IV Adkin’s other geological work

Rejection of his paper had been a disappointing episode for Adkin, and he did not return to geology until 1919, when he noticed work published by Cotton (1918) on the Horowhenua coastal plain, a location Adkin had written about previously (Adkin, 1911a). Cotton’s (1918) paper dealt with geomorphic development of the area, referring to Adkin’s (1911a) paper under the subheading ‘Another Alternative Explanation’, and stating (Cotton, 1918: 219): ‘An account of the geological history which diverges considerably from that assumed here was given by Adkin … must be discarded as he had no means of correlation … It is not clear, however, to what base-level he ascribes the planation’. Of Adkin’s (1911a) work, Cotton (1918: 220) adds: ‘The account is somewhat difficult to follow and his conclusion … is an extremely doubtful one’. Cotton (1918: 220) concluded, rather patronizingly: ‘Adkin’s work is obviously based on large amounts of careful fieldwork; and his mapping in the Ohau River district (Horowhenua) is extremely useful’. In response, Adkin undertook some further analysis, and submitted a paper for publication in Transactions of the New Zealand Institute, but it was rejected and returned to Adkin (Dreaver, 1997: 122), and Adkin claimed in his diary on 22 November 1919 that ‘Dr Cotton has used his influence to suppress my paper criticizing his … there can be no doubt of this … the referee’s report shows Cotton’s influence’. The paper was finally accepted the following year, and in it Adkin (1919: 113) was forthright, noting ‘one of the chief causes of Cotton’s divergent opinion … is the greater complexity of the lowland than he at present recognizes'.

This clash with Cotton appeared to re-energize Adkin’s interest in geology after a six-year gap, and he undertook studies of a river capture near Levin (Adkin, 1920) and of uplift around Porirua Harbour (Adkin, 1921a) to the south. Adkin (1921a) hypothesized the 1855 earthquake that caused uplift around Turakirae Head, Cook Strait (e.g. Wellman, 1967), had also uplifted the shoreline ~1 m around Porirua, narrowing the harbour inlet.

Further highlights of Adkin’s geoscientific work included work on an engineering geology issue related to the construction of the Mangahao hydro-electric scheme (Adkin, 1921b), a topographic map for the New Zealand Government (Adkin, 1924), a paper on the origin of the Manawatu Gorge (Adkin, 1930), which is the only transverse drainage across the Tararua Range, and work on hydrogeology (Adkin, 1948a). Aged 57, and after a lifetime as an amateur geoscientist, Adkin finally took up paid employment as a professional geoscientist, as a Palaeontologist’s Assistant at the New Zealand Geological Survey (NZGS), Wellington. Perhaps instilled with more confidence as an employee of the NZGS, Adkin published a paper in 1949 that revisited the study he had rejected for publication in 1911, on the long-term geomorphic development of the Tararuas (Adkin, 1949). Adkin (1949: 260) wrote ‘these views … were not acceptable in 1911 and their placing on record at that date was denied’. Of Cotton’s (1918) theory, Adkin (1949: 261) robustly stated: ‘it has become the current fashion to ascribe the major physiographic trends (ridges and drainage lines) to adjustment to structure. Among the adherents … reasoning in a circle seems to have occurred’. Adkin commented that ‘Professor Cotton got up to annihilate me but found he had to agree to much of my thesis' (Adkin Diary, 22 May 1947). Adkin’s theory of crustal compression causing uplift of the Tararuas, 36 years after he had first postulated it, was now accepted.

Adkin also published on the effect of tectonics on deposits around Paekakariki (Adkin, 1951a), his work at the NZGS produced three bibliographic articles (1951b, 1951c; 1952a), and he also published a study on river avulsion in Otago (Adkin, 1953a). Another paper reviewed evidence for fault systems in the southern Tararua Range (Adkin, 1954a), contextualised within a regional tectonic context. Adkin (1954b) also published evidence for normal faulting in the Wellington area, which contrasted with the prevailing view (e.g. Wellman, 1955) that all faulting in the Wellington area was strike-slip. Adkin’s final geological work reflects his skills for being a meticulous recorder of information, including abstracts of papers published on New Zealand geology (Adkin, 1951b, 1951c, 1952a), a bibliographic index of New Zealand stratigraphic terminology (Adkin, 1954c), part of a Geological Survey Bulletin (Adkin, 1953b) and an article outlining locations of early exploration reports during James Hector’s directorship of the Geological Survey of New Zealand (Adkin, 1954d).

Many of Adkin’s later publications were focused on his other interest, Māori archaeology (Adkin, 1941, 1942, 1948b, 1950a, 1950b, 1950c, 1951d, 1952b, 1955, 1956, 1957a, 1959a, 1959b, 1959c, 1960, 1961, 1962, 1963; Adkin and Collins, 1967). He also wrote several articles linking his two great interests, geology and Māori archaeology (Adkin, 1951e, 1952c, 1957b, 1957c).

V Conclusions

Adkin retired from the NZGS aged 67 in 1955, and his 1963 article was his penultimate published work (a co-authored work with BW Collins was published posthumously), before he died in 1964. In particular, he made a huge contribution (as an amateur scholar) to knowledge of the geology and geomorphology of the lower North Island of New Zealand. His skills as a thorough collector and recorder of information allowed him to overcome his lack of university training. Adkin was a pioneer, in terms of his conviction for a limited Pleistocene glaciation of the Tararua Range, and his idea of crustal compression and uplift of the range in 1909 were ahead of their time. In conclusion, despite the lack of any university training, Adkin made significant contributions to geology (and archaeology), many of them while he was employed in a demanding occupation (farming) unrelated to his chosen fields of inquiry, but which gave him opportunities to observe the landscape. His self-taught status meant he was not bounded by prevailing theories. Adkin’s life is comprehensively recorded by Dreaver (1997), and Adkin’s work (geological field notebooks) can be accessed at the Geological and Nuclear Sciences (GNS) library, Lower Hutt, Wellington, New Zealand.