Palaeoecological studies of selected mires in the Craven District of West Yorkshire with special reference to the late Devensian period and the Ulmus decline

(1) Percentage and absolute pollen diagrams are presented for a lowland site, Sniddle Moss, and two upland sites, Thieves' Moss and Sunset Hole, in the Ingleborough Region, the Craven District, north-west Yorkshire. (2) The analysis of the earliest sediments of Sniddle Moss and Thieves' Moss suggests the existence of a Lateglacial sequence. A reconstruction of the regional vegetational succession mainly based on the Sniddle Moss 4 data reveals that at first a very open vegetation and a species-rich calcareous grassland were formed. The spread of juniper scrub preceded the expansion of tree birches. It is tentatively inferred that the early part of the Lateglacial is interrupted by a phase of deteriorating climate and that the relative warmth of the Lateglacial Interstadial gives way to a further and more prolonged deterioration. The climatic deterioration of the Younger Dryas Period is clearly registered by the decline of thermophilous taxa and the local severity of conditions demonstrated by the increased abundance of chianophilous taxa and other montane herbs in the profile of both Sniddle Moss (4) and Thieves' Moss (2). (3) The ensuing amelioration in climate at the beginning of the Flandrian (early and middle) is traced. (4) It is suggested that the woodland vegetation was being managed by the local Mesolithic and early Neolithic population prior to the first classical elm decline of the Atlantic/Sub-Boreal transition (c. 5000 BP). (5) Pollen analysis involving continuous sampling across the elm decline at Sniddle Moss (9) and Sunset Hole permitted a detailed reconstruction of the vegetational changes and the observation of the nature of the elm curve. A chronology for Sniddle Moss (9) is provided by radiocarbon dating. The initial recovery of elms is dated to 4710±45 BP and the second elm decline to about 4520 BP. The possible factors contributing to the first classical elm decline and the changes in the elm curve immediately following the first decline are considered.