The Impact of Late Prehistoric Cultures on the Vegetation of the North York Moors

Abstract

Palynological data are presented from five sites on the North York Moors for changes in vegetation from Mesolithic times to the present day. Attention is focused on the late prehistoric period for which a considerable body of archaeological evidence is available. The traditional view of the importance of the middle Bronze Age period is challenged and the theory propounded that Iron Age and Romano-British cultures had a greater effect on vegetation and soils in this area than has previously been realized. A mechanism is suggested for man-induced change over the late prehistoric period and a tentative assessment is made of its long-term effects on the regional ecology. THE North York Moors offer ample research material to both the palynologist and the archaeologist. The area forms an isolated block of Jurassic rocks with clearly defined boundaries, crossed by a multitude of peat-filled glacial drainage channels and capped by an expanse of more recent blanket peat. Settlement is for the most part confined to the dales and the fringing lowlands, leaving the high moors as an area of rough grazing and, more recently, recreational land, where many archaeological remains have survived intact from the prehistoric and historic periods. The traditional view (Elgee, 1912, 1914) of the Callunetum as the 'climax' vegetation in this region of relatively low rainfall (only the highest areas receive over iooo mm p.a.) has been discredited by the work of palynologists such as Dimbleby (1952, i96i) and Simmons (1969). Over 30 sites scattered throughout the Moors (Fig. I) testify to a former forest cover, the disappearance of which is attributable to the hand of man. However, although the general sequence of events is well established, the details of the human impact on the vegetation of more restricted areas have not received a great deal of attention from palynologists. In this study a close examination is made of the effects of Bronze Age, Iron Age and RomanoBritish cultures on the vegetation of a small area in the eastern-central part of the Moors (Fig. i). A brief account of vegetation development in the area throughout the post-glacial period will be made to enable the late prehistoric period to be seen in context, but no detailed analysis will be attempted of ecological changes in the preceding or succeeding periods. Within the study area, five sites were examined in a variety of topographical situations (Fig. 2). The pivot site for the study was Fen Bogs, a 20 ha valley mire at the head of Newton Dale at an altitude of 164 m O.D. Peat remains of a maximum depth of i-8 m have been accumulating since the early post-glacial period and overlie a late-glacial solifluction clay. Field stratigraphy borings revealed a succession from carr woodland (Betula, Alnus, Salix) to Phragmites swamp, which was replaced by acidophilous vegetation dominated by Sphagnum, Eriophorum and Calluna probably as a result of drainage schemes associated with the creation of pastureland and the construction of the Whitby-Pickering railway in 1836. Peat deposits at the upland site of May Moss (259 m O.D.) have accumulated in the basins of two moorland streams and have amalgamated to form an area of blanket peat covering Ioo ha. 284 This content downloaded from 157.55.39.25 on Tue, 02 Aug 2016 04:40:58 UTC All use subject to http://about.jstor.org/terms Vegetation of the North York Moors 285