Other formats

    TEI XML file   ePub eBook file  


    mail icontwitter iconBlogspot iconrss icon

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

Storage pits

Storage pits

One of the often-cited achievements of Māori horticulture was the development of kūmara storage. Kūmara was stored in pits dug into slopes, in ridge crests, or the flat surfaces of areas in or close to sites of occupation. 27 The function of storage pits was to provide a storage space of even temperature (never less than about 4°C), waterproof, well drained and rat-proof. Kūmara will be destroyed if exposed to temperatures less than 4°C, and would not survive if left in the open or in raised-house page 71 stores throughout the New Zealand winter. No doubt general security in the event of warfare was also a factor. Indeed, open rectangular storage pits are often in apparently awkward positions among the ditch and bank defences of pā. They were perhaps placed there to amplify the defences and not just to have them out of the way of the living spaces within the pā.

Storage pits are very distinctive from the air. On the East Coast and in Taranaki, the Waikato and Hawke's Bay, they appear as open depressions, rectangular in shape, as much as 8 m long and 4 m wide. Typically they measure about 4 by 2 m in plan and are 1 m deep. The depths are fairly consistently at just over 1 m, suggesting that the tubers were stacked one on top of the other rather than on racks; any deeper than 1 m and the lower tubers would have been crushed or bruised leading to rapid decay. Pits may have an earthed-up rim around the outside edge of the depression, with a drain outside the rim leading away to the edge of the ridge. The raised rim may be the remnants of the earthed-over roof of the pit (now decayed and collapsed into the pit cavity) or a bank placed under the eaves, while the drain served a function similar to that of a gutter at the lower edge of the roof. When excavated, the bottoms of pits are commonly found to have a central row of postholes at their base to support a ridge pole for a roof. There may also be an interior drain, at the foot of the earth walls, designed to carry away water from the stored crop inside the pit. Sometimes pits were cut from clay topsoils down into porous sandy subsoils, again offering drainage at the base. 28

In regions with deep, easily worked subsoils, such as Taranaki or the Bay of Plenty, the completely subterranean cave pit was more common. In these, the roof of the pit (the immediate subsurface of the ground) is dug in such a fashion that it curves over like the top of a bell. This makes the roof of the pit very strong. Underground, the pit was circular or oval in plan and could be as much as 2 to 3 m wide by 2 m deep. The vertical passage into the top of the pit was about 30-60 cm in diameter and sealed by a tight-fitting lid, so that the whole structure did not lie above the general level of the ground. 29 This type of pit, known as a 'rua' by archaeologists, was also cut into the defensive banks of pā, in which case the entrance passage was horizontal. These pits were very economical of surface space within a constricted area such as a pā. Some pits also appear to have been used to gather and store water. Today, such pits are generally not found open at the top, except in areas where the forest has grown back over the site and prevented erosion and stock tracking. Typically the whole of the pit collapses in under the weight of stock and leaves a distinct more or less circular depression up to 2 m in diameter. In some places in Taranaki, the Waikato or the Bay of Plenty, the whole surface of a pā may be pockmarked with such depressions.

There is now general agreement that pits were not for houses, 30 as was once thought. The storage function was generally recognised as late as the 1920s, 31 but as pits fell out of widespread use a 'pit dwelling' theory took hold, originating particularly among scholars working in the South Island. 32 The accepted interpretation, kūmara storage, nevertheless raises some unresolved questions. Were pits in use from earliest times, as the existence of their Polynesian precursors would suggest? No pit found is as old as the earliest settlement contemplated in New Zealand. The oldest examples are about 700 years old at Skippers Ridge and Sarah's Gully in the Coromandel and 600 years old in inland Tolaga Bay on the East Coast. 33 Most pits when excavated and dated by radiocarbon prove to be younger. The late age for pits has been used to suggest that horticulture was introduced to New Zealand some time after first settlement, after large animals like the moa had been hunted to extinction. 34 Such a view is not generally accepted today.

There are several further points that may be made. First, the regional distribution of pits follows very closely the distribution expected for gardening on soil and climatic grounds. This in itself points to their function. Second, when excavated, pits are often found intricately cut into one another, showing that pits were deliberately filled back in, and new ones cut at a slightly different location but overlapping the former one. Estimates have been made that only a small proportion of the total number of storage pits can be seen from the surface. 35 The purpose of cutting pits again and again was to remove the risk of pathogenic fungi establishing on the walls, and passing the infection from one year's crop to the next.

Sites which show pre-European horticultural land uses have not survived particularly well, although as we have seen there are some notable exceptions, particularly where soils are too stony to plough. Unfortunately, the areas that are most useful today for horticulture were also the areas used by pre-European Māori. As a result much of the evidence of earlier Māori gardening and other related sites have been destroyed, for example in page break
Whenuanui, a pā with many raised-rim storage pits on the high terrace of the Waipāoa River near Pūhā, East Coast

Whenuanui, a pā with many raised-rim storage pits on the high terrace of the Waipāoa River near Pūhā, East Coast

In this oblique view, raised-rim pits show clearly within the defended area of the pā. A Pleistocene (ice-age) river-terrace surface has been cut by gully erosion (foreground) and the main river (in distance), leaving a narrow neck at the right of the picture. This neck has been defended by two sections of ditch and bank, only one of which shows here. The view is to the south-west in afternoon light. The largest of the pits is about 7 m square. The main defended area is about 100 by 200 m in extent.

the Tauranga vicinity, so the earliest aerial photographs are important records. In the pre-European period, later gardening always destroyed the archaeological evidence of earlier gardening simply by turning over the soil again and again, so that finding the earliest age of horticulture has proven difficult. There are important exceptions to the general situation of surface destruction. The individual plots of Māori horticulture were small; a whānau would seldom cultivate more than 2 ha. The locations in the landscape where this cultivation was carried out are correspondingly small. Because individual gardening areas were so small they were often able to be located on narrow ridges with the primary purpose of escaping frost. In this circumstance they would not be subject to modern ploughing and these small patches cumulatively covered large areas in some regions. 36

Overall then, the value of aerial photography in documenting horticulture has been considerable, with perhaps better established results than in any other area of application of the technique in New Zealand archaeology. Because of gardening's extensive nature, the difficulty of seeing patterns from a ground view, and indeed the destruction wrought by modern horticultural practice, aerial photography has given insights to a level of detail that is only matched by the first written observations from the Endeavour in 1769. 37