This dataset spans the Sinemurian-Pliensbachian boundary of the Llanbedr (Mochras Farm) drill core that was drilled onshore in the Cardigan Bay Basin, Wales, UK. This dataset contains 1. Micro-, macro-charcoal data and palynofacies, obtained at the University of Exeter (Streatham campus), UK, 2. Clay mineralogical data (X-ray diffraction (XRD)) obtained at the University of Burgundy, France, in collaboration with Jean-François Deconinck, 3. Carbon-isotope data, TOC and carbonate content, obtained at the University of Exeter (Penryn campus), UK. The dataset was created within the scope of the JET project (Integrated understanding of Early Jurassic Earth system and timescale) - https://gtr.ukri.org/projects?ref=NE%2FN018508%2F This project has received funding from the International Continental Scientific Drilling Programme (ICDP) and the UK Natural Environment Research Council (NERC). The PhD-project within this dataset was created is funded by the University of Exeter, UK.