Abstract Karstification produces a unique and spatially complex architecture of accommodation space for the accumulation of later sediments. The sedimentary record within caves can act as a repository for stratigraphic and palaeoenvironmental information that has been locally removed by subsequent surface erosion. Caves and karst also allow for the preservation of biota not usually found in the fossil record. Pennsylvanian palaeokarst from Illinois, USA, illustrate the potential of ancient caves as a home for ‘lost stratigraphy’. These palaeocaves have dissolutional features associated with contemporaneous sediment influx (paragenesis), indicating that speleogenesis and cave sediment deposition were synchronous. These features also provide evidence of changing water tables. The fill within the caves suggests multiple flood events on the surface. The enclosed biota contains rare upland plants, such as conifers, as well as scorpions. Both plants and animals preserve original organic constituents. The presence of charcoal, as well as diagnostic polyaromatic hydrocarbons, point to wildfires and thus dry episodes on the land surface. The cave fills are outliers from correlative formations in the region. The filled voids of these ancient caves thus fill palaeontological, palaeoenvironmental, and stratigraphic gaps.

Abstract The Lower and Middle Coal Measures of Langsettian (Westphalian A) and Duckmantian (Westphalian B) age (together equals Bashkirian in part) in Britain comprise an alternation of clastic sediments and coal deposited on coastal and alluvial plains over a period of 2–3.5 million years, depending on which time scale is accepted. In both the Pennine and South Wales Basins there are no obvious unconformities. Many of the clastic sequences show evidence of rapid sedimentation (burial of trees, bivalve escape burrows) that may suggest that a significant amount of time is taken up during the peat-forming intervals. Thickness data from a range of boreholes that record continuous sections through this time period were collated. Coal and sediment thicknesses, as well as coal to sediment ratios, are compared both within and across the basins. Data on the coals has allowed consideration of the time taken to deposit the peats. This work considers the compaction of the peat to coal, as well as a range of peat accumulation rates. Assuming the largest de-compaction rates and slowest accumulation rates of the coal formation, less than 50% of the allocated time can be accounted for. In addition however, calculations suggest that peat formation accounts for less than 25% of the total time taken for sediment accumulation. It is suspected that there are major time gaps in the sequences, most probably occurring between seat-earths and coal and within the coals, and it is believed that this finding has significance for the debate over short-term climate changes in the Carboniferous and the causes of peat and sediment alternations. Supplementary material: Borehole thickness data and references are available at http://www.geolsoc.org.uk/SUP18788

Standing lycopsid trees occur at 60 or more horizons within the 1425-m-thick coal-bearing interval of the classic Carboniferous section at Joggins, with one of the most consistently productive intervals occurring between Coals 29 (Fundy seam) and 32 of Logan (1845) . Erect lepidodendrid trees, invariably rooted within an organic-rich substrate, are best preserved when entombed by heterolithic sandstone/mudstone units on the order of 3–4 m thick, inferred to represent the recurring overtopping of distributary channels of similar thickness. The setting of these forests and associated sediments is interpreted as a disturbance-prone interdistributary wetland system. The heterogeneity and disturbance inherent to this dynamic sedimentary environment are in accord with the floral record of the fossil forests and interpretation of the peat-forming wetlands as topogenous, rheotrophic forest swamps. Candidates for the erect, Stigmaria -bearing trees, which range in diameter (dbh) from 25 to 50 cm, are found in prostrate compressions and represent a broad range of ecological preferences amongst the Lycopsida. This record, which is not significantly time averaged, closely parallels the megaspore record from thin peaty soils in which they are rooted, but differs significantly from the miospore record in studies of other, thicker coals. Dominant megaspores are Tuberculatisporites mamillarus and Cystosporites diabolicus , derived from Sigillaria and Diaphorodendron / Lepidodendron respectively. Intervening beds preserve a record of an extra-mire flora composed in the main of seed-bearing pteridosperms and gymnosperms (and ?progymnosperms). Reproductive adaptation to disturbance appears to have played a key role in ecological partitioning of plant communities within these wetlands. Burial of lycopsid trees by onset of heterolithic deposition resulted in the demise of entire forest stands. Disturbancetolerant Calamites regenerated in the episodically accruing sediment around the dead and dying lycopsid stands, a succession identified here as typical of Euramerican fossil forests. Rapid, ongoing subsidence of the basin accommodated the submergence of the fossil forests, and abiotic disturbance inherent to the seasonal climate facilitated their episodic entombment. Disturbance is inferred to have been mediated by short-term (?seasonal) precipitation flux as suggested by the heterolithic strata and in the record of charred lycopsid trees, recording wildfire most probably ignited by lightning. Within this fossil forest interval is found a glimpse of animal life within the wetland ecosystem beyond the confines of the tree hollows, whence the bulk of the terrestrial faunal record of Joggins historically derives.