1. Introduction Natural, lightning-initiated fires occur today in every vegetation biome including everwet tropical rainforest and frigid tundra (Racine, Dennis & Patterson, 1985; Sanford et al. 1985). Recently, the importance of fire in influencing earth surface processes has received con- siderable attention; it is now known that fire plays a crucial role in the global carbon cycle (Clark, 1997), shapes the character and evolutionary development of many terrestrial ecosystems (Walter, 1973) and alters cycles of erosion and deposition (Meyer & Wells, 1997). The frequency, geographic area and intensity of fire events in a given region, and thus their impact on plant ecology and the physical environment, are strongly influenced by rainfall magnitude and season- ality (Chandler et al. 1983). Regions with everwet, non-seasonal climates are characterized by large, low frequency (every 100–1000 years), high intensity fire events, whilst in seasonally-dry regions fires occur much more frequently (annually in some places) but are of smaller size and lower intensity (Scott & Jones, 1994; Falcon-Lang, 2000). Recently there has been great interest in trying to understand the nature and significance of fire in Pre- Quaternary times (Scott, Moore & Brayshaw, 2000). The occurrence of Pre-Quaternary fires may be recog- nized by the presence of fossil charcoal incorporated into sedimentary and extrusive igneous rocks (Scott, 1989, 1990). Early workers called this substance fusain and came to conflicting conclusions about its origin (see Robinson, Chaloner & Jones, 1997, for a review), but recent chemical and physical studies have con- firmed that fusain is fossilized charcoal, the product of wildfire (Jones & Chaloner, 1991). An important fea- ture of all charcoal is its exquisite preservation of three-dimensional plant anatomy, a condition related to the fact that the plant material was made chemically inert through loss of volatiles before it entered the geo- logical record (Scott, 1989). Recent work on Carboniferous charcoal deposits has demonstrated that a wealth of palaeoecological data may be extracted from this remarkable fossil material (Scott & Jones, 1994). For example, through a comparison of the distribution of charred and uncharred plant fossils within the facies context, dis- crete fire-prone plant communities may be identified (Batten, 1998; Falcon-Lang, 1998, 1999a, 2000; Falcon-Lang & Scott, 2000). Additionally, integration Geol. Mag. 138 (5), 2001, pp. 563–576. © 2001 Cambridge University Press DOI: 10.1017/S0016756801005714 Printed in the United Kingdom 563 Fire-prone plant communities and palaeoclimate of a Late Cretaceous fluvial to estuarine environment, Pecínov quarry, Czech Republic H. J. FALCON-LANG*, J. KVAC ˇ EK† & D. ULIC ˇ NY ´ ‡ *British Antarctic Survey, High Cross, Madingley Rd, Cambridge CB3 0ET, UK †Department of Palaeontology, National Museum, Václavské nám. 68, 115 79 Praha 1, Czech Republic ‡Geophysical Institute, Czech Academy of Sciences, Bocni II/1401, 141 31 Praha 4, Czech Republic (Received 1 December 2000; accepted 19 June 2001) Abstract – The botanical identity and facies distribution of fossil charcoal is described from Middle to Late Cenomanian (90–94Ma) fluvial to estuarine units at Pecínov quarry, near Prague, Czech Republic. Braided alluvial facies associations contain charred conifer woods (family Pinaceae) possi- bly derived from upland forest fires, and abundant charred angiosperm woods, flowers and inflores- cences (families Lauraceae and ?Platanaceae) derived from riparian gallery forest fires (Unit 2). Retrogradational coastal salt marsh facies associations contain abundant charred conifer wood (fami- lies Cheirolepidiaceae and Cupressaceae/Taxodiaceae) derived from fires in halophytic backswamp forest, and rare pinaceous charred cones and lauraceous angiosperm wood washed downstream from fires further inland (Units 3–4). Progradational coastal facies associations within an estuary mouth setting contain abundant charred conifer wood (family Cupressaceae/Taxodiaceae), common taxodia- ceous conifer and angiosperm leaves, fern rachises, and lycopsid stems derived from fires in mesic backswamp taxodiaceous forests and supra-tidal fern-lycopsid thickets (Unit 5). Growth rings in angiosperm and conifer woods, leaf physiognomy and computer models indicate that climate was equable, warm and humid, but that there was a short annual dry season; most fires probably occurred during these annual drought periods. The abundance of charcoal and the diversity of taxa preserved in this state indicate that nearly all plant communities were fire-prone. Physiognomically, the Pecínov flora resembles present-day seasonally-dry subtropical forests where fires are a common occurrence. * Author for correspondence, present address: Department of Earth Sciences, Dalhousie University, Halifax, Nova Scotia B3H 3J5, Canada; e-mail hfalconl@is.dal.ca