7.2 Environmental Evidence

By the Late Iron Age much of Scotland had been deforested; though in the northern Highlands this may have been through a combination of human and climatic factors as well as peat formation (Tipping 1994, 37). While many sites show the increasingly normal evidence of hazel, birch and alder, clearly some areas continued to have access to oak and even pine.

Information is available from a number of sites. For example, charcoal and wood remains at Crosskirk broch, Caithness (MHG39521) showed aspen, alder, birch, hazel, juniper, pine, rowan and willow (Dickson and Dickson 2000, 108). At Upper Suisgill, Sutherland, the Iron Age landscape was dominated by pine and birch, interspersed with open heathland (MHG9345; Barclay 1985, 192). Closer to the Dornoch Firth, at Cyderhall, Sutherland, a quantity of oak survived. This has been interpreted as possibly used for roofing for the roundhouse there, with speculation that the oak was sourced locally (MHG11834; Dickson and Dickson 2000, 109). This view has been supported by environmental analysis from more recent excavations at the nearby Dornoch Bridge quarry (Young et al 2019). The multiperiod analysis at Lairg provides useful data, including evidence for the utilisation of oak resources along with the typical hazel, willow and alder. Pollen suggests intense grazing rather than agricultural use in the area (McCullagh and Tipping 1998, 210–211). The recent work in advance of development around Inverness has resulted in a growing body of data, and research in progress on macrofossil evidence will look at issues of wood source and management. Charcoal is currently being examined from Culduthel, Inverness by Scott Timpany to shed light on fuel use and management in this important industrial site. This recent work highlights why information from local studies still needs to be gathered to assess the situation on a local level.

Studies suggest that the earliest Iron Age was relatively dry, but an abrupt change around 750 BC resulted in a much wetter climate (ScARF Iron Age section 3.2). More local well-dated data is needed for the Highlands (see Geary et al 2020 for a focus on Ireland during this period). A study in Wester Ross revealed increased coastal dune formation, probably due to stormy weather (Wilson 2002, Smith et al 2019). This spell of a wetter climate, lasting until c AD 200, relates to peat formation in the Highlands and elsewhere. For example, during the first centuries AD, peat formed over House 3 at Lairg (McCullagh and Tipping 1998, 44). However, as noted in Chapter 3, regional differences occurred and individual data needs to be assembled including an assessment of upland versus lowland differences.

A survey analysing evidence of sea level, including from northwest Scotland and Wick, suggested that during the last 2000 years sea level has been either been falling or near stable, though issues of land isostatic uplift also need to be factored in (Smith et al 2019). As for other periods, this information for the coastal areas needs to be integrated with settlement evidence. In particular, it will affect the feasibility of coastal cave occupation.

Other localised data is still awaiting publication including several key sites such as Bellfield, North Kessock in Easter Ross; Culduthel and other excavations in Inverness; Clachtoll broch, northwest Sutherland; Dun Deardail hillfort, Lochaber; and High Pasture Cave, Skye. AOC Archaeology is currently working with Durham University on the analysis of environmental remains from a number of Caithness brochs along with Clachtoll broch. Together these sites should provide detailed information on landscape and subsistence in the Iron Age (Heald et al forthcoming; Andy Heald pers comm). The geographical spread of these sites will provide good data for much of the Highlands, especially when integrated with other published sites (Chapter 7.3). Areas from Nairn, Badenoch and Strathspey and southwest Lochaber have sparse data, however, and could be targeted in future research.

Crannog sites also offer great potential for environmental data. Few have been excavated in modern times in the Highlands, but artefactual and environmental information is likely to survive in the form of structural timbers that are in abundance in certain parts of Highland. Many have Iron Age, and indeed later, occupation.