This dataset contains geochemical measurements which quantify the major and trace element concentrations of Precambrian (Proterozoic) and Paleozoic (541–251 Mya) mudstones. Sampled mudstones are listed under their formation name, with information on the locations of each outcrop belt and further details on lithological characteristics, including environment of formation, freely available on the British Geological Survey Lexicon of named rock units (https://www.bgs.ac.uk/technologies/the-bgs-lexicon-of-named-rock-units/) and Government of Canada weblex (https://weblex.canada.ca/weblexnet4/weblex_e.aspx), for UK and Canadian samples, respectively. Stratigraphic age is given in accordance to the GSA geological timescale v.5.0. Following sampling, specific methodologies for preparation for major and trace element analysis, conducted on an Agilent 5100, are provided in the Methodology. The data was collected to understand changes in weathering intensity coeval with the Paleozoic expansion of land plants. The major element data was needed to: 1) determine how much sample was required for subsequent Lithium isotope analyses (data from which are separately uploaded to the repository); and 2) to ensure similarity of source between samples compared across our study. The tabulated major element analyses were compared at different temporal stages of plant evolution through the Paleozoic. Samples were collected by the University of Cambridge. Major element data was obtained by William McMahon, and supervised by Edward Tipper and Mohd Tarique and Emily Stevenson.
