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Ngā Tohuwhenua Mai Te Rangi: A New Zealand Archeology in Aerial Photographs

Stonefields

Stonefields

The importance of gravelly or stony soils has already been stressed. The gravels could be added, or naturally stony ground could be selected, and enhanced by removing the larger stones and placing them in rows or mounds. Such techniques were extensively used in the volcanic soils of Auckland and Northland, with smaller areas of volcanic soils at Cape Runaway in the eastern Bay of Plenty. Of course, these soils were both friable (because there had not been sufficient weathering to create clays) and of high natural fertility. Similar horticultural practice was common on the volcanic soils of Central Polynesia and Hawaii, 8 and the potential of such soils would have been readily recognised by the first Polynesians entering New Zealand. 9

Gardens on stony soils of non-volcanic origin are common on the coastal strip in Hawke's Bay, the Wai-rarapa and the north-east of the South Island. 10 The coastal strip had no frosts, and had readily warmed and friable soils. Stone rows are rare inland, but they do exist, for example, 15 km inland in the Tukituki River valley, central Hawke's Bay. 11 In these cases, Māori built extensive lines and areas of mounds and stone rows. At Palliser Bay, such soils appear to have been gardened early in pre-European history. The Palliser Bay case is particularly interesting because here the mapping of the stone rows over a coastal strip some 20 km long and up to 500 m wide was done using purpose-flown, low-level aerial photography. The photographs were used as a map base and supplemented by Helen Leach's detailed field observations, 12 although none of the photographs have been published.

Radiocarbon dates at Palliser Bay go back as early as the twelfth century, but most are in the fifteenth century. 13 The abandonment in pre-European times of the garden areas in Palliser Bay that were evidently once valued has been much discussed. This area approaches the climatic margins of kūmara horticulture. Another 2° of latitude (or 400 km) south, a drop in mean temperature with the corresponding shortening of growing season, and horticulture was not possible at all. 14 It has been argued by Foss and Helen Leach, the original investigators, that a fire-induced reduction in forest and increased erosion, exacerbated by a long-term deterioration in climate, led to climatic marginality for gardening and the destruction of fishing grounds. 15

I favour the destruction by fire of a fragile coastal page break
Stone mounds, part of the gardening system at Pouērua

Stone mounds, part of the gardening system at Pouērua

The many small mounds are about 4 m across at their base. The functions of such mounds are difficult to determine. They may have served to clear the stony soils of the old lava flow so that the friable and fertile soils that resulted were more easily tilled. Alternatively, they may originally have consisted of heaped-up mounds of soils, organic compost and stones, on which plants were grown. The topsoils have subsequently been eroded away from the surface leaving a mound of stones which does not look as if it could have been gardened. A further possibility is that the vines of plants such as kūmara or yam were trained over the mounds. At top are some larger lava domes (about 25 m across). These have had stone stripped from their surfaces and placed in walls on their perimeter. At bottom and bottom right, a heavier fall of ash has reduced the need to create stone mounds. Here there are barely perceptible lines in the small valley floors which are either trench garden boundaries or track ways. Also showing are lines of stone walls constructed in the nineteenth century.

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Stone rows delineating garden boundaries near Okoropunga, on the Wairarapa east coast

Stone rows delineating garden boundaries near Okoropunga, on the Wairarapa east coast

The individual patches are 10 to 30 m across and 150 m from the foot of the steep slope to the sea. This view is taken looking to the south-west. The appearance of rows running parallel to the beach, further dividing the gardens into rectangular plots, is somewhat misleading. The lines parallel to the beach are ridges of stones thrown up by Storms at the back of former beaches. Over thousands of years, these beaches have been lifted by earthquakes out of the reach of wave-action. The main stone row boundaries have been constructed at right angles over the line of the beach ridges, although some of the ridges themselves may have been enhanced and also served to mark the boundaries of gardens. Some of the stones in the garden rows were taken from the depressions (borrow-pits) which show along the top edge of the principal beach ridge. Throughout the Wairarapa, the original topsoils that existed in these areas have been removed by fierce squally winds, thus causing the abandonment of the gardens. In their original form the gardens would have been fringed with coastal forest and protected from wind.

page 66 forest, combined with wind-stripping of soils, as specific explanations for this sudden early flourishing and then abandonment of horticulture at Palliser Bay. When the coastal forest was initially burnt, the soils had a high degree of fertility. However, these soils were probably not fallowed; they were used continuously perhaps over five years following island-Polynesian models—and eventually used to exhaustion in that short period. However, detecting a fallow period as short as five or even 10 years is beyond the precision-range of radiocarbon dating, 16 so we shall never have satisfactory positive evidence of this particular practice. It does explain the facts as we know them. Continuous use was not a sustainable practice in the peculiar environmental conditions of the south-eastern North Island. Once the protective coastal forest had been burnt, and artificial wind protection such as stone rows had been abandoned, the soils were progressively blown away by the strong, turbulent winds for which this coast is notorious.

In stony areas the presence of mounds, rows and other features offers the enticing prospect of furthering the understanding of Māori gardening practices. We know that Polynesians were very particular about the arrangement of plots and the paths through them. One reason was the tapu that attached to growing plants at certain stages, and there may have been more general considerations of what would now be called 'property'. The rows and mounds therefore had functions other than just the placement of stone waste removed from the plot itself. The stones are often arranged in definite patterns, with the rows running down the slope. In this pattern they are thought to reflect a typical Polynesian subdivision of the landscape into individual or whānau plots. 17 These garden plots come close to offering a sense of property, however ambiguous and difficult to interpret, in pre-European society. Helen Leach has estimated that, for the Auckland area, plots ranged from 80 to 300 m long and 25 to 60 m wide, i.e., from 0.2 to 1.8 ha. These larger areas were subdivided into smaller areas of about 10 by 20 m (0.02 ha). At Anaura Bay on the East Coast the plots recorded by the Endeavour observers were up to 2 ha in area and subdivided into plots of 0.04 to 0.06 ha in area. 18 Some of the aerial photographs presented here show plots of just these sizes, for example, those at Okoropunga on the Wairarapa coast.

Other purposes that have been suggested for the stones set aside from fields are: field shelters or houses; 19 'shelter belts' for the crops; markers for the sides of paths (important in avoiding breaches of tapu); 20 areas of particularly high ground temperatures for the propagation of young plants in spring; 21 and finally, elevated, well-drained places over which the running vines of yam or kūmara could be placed.