We don't have synonyms for red beds yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are red bean, red ned and redbed.
(N) :
(or redbeds) sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides.
(N) :
(or redbeds) sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides.