These data accompany a manuscript, titled: Stream and Slope Weathering Effects on Organic-rich Mudstone Geochemistry and Implications for Hydrocarbon Source Rock Assessment: A Bowland Shale Case Study All files with prefix 'Man_1' relate to this submission. The manuscript was submitted to the journal Chemical Geology in December 2016. Data include: 1) A range of photographs from the outcrop, drill cores, sub-samples, 'weathering grades' and thin section microphotographs from the Bowland Shale; 2) The results of mineralogical (whole rock powder x-ray diffraction; XRD) analyses for 18 subsamples; 3) The results of inorganic geochemical analyses (LECO elemental C and S, x-ray fluorescence major and trace elements) for 18 subsamples; 4) The results of organic geochemical analyses (Rock-Eval pyrolysis, d13Corg) for 20 subsamples; 5) RStudio scripts used to conduct statistical analyses (e.g., Principal Components Analysis) and generation of figures.