Nature and distribution of loess in Canterbury, New Zealand

Abstract

Abstract Loess of variable thickness occurs over 26% of the land surface of Canterbury. Areas where loess is currently accumulating, areas where loess ceased to accumulate at the close of the last glaciation and areas where loess has been transported and redeposited by water are shown on maps. It is suggested that the extensive thick deposits of loess on the Canterbury down-lands and foothills were derived from pre-existing loess deposits on the fan surfaces of the Canterbury Plains. The phase of relocation of the loess was of brief duration, probably 2000 years, and was followed by a period of deposition of younger loess on to the now deflated fan surfaces of the Plains. It is proposed to call the thick loess layers which were deposited during brief periods in the late Pleistocene “post-stadial loess”. Loess which accumulated at a slower rate on the fan surfaces adjacent to the major rivers crossing the Plains is designated “interstadial loess”. Recent or Post-glacial loess is an example of inter-stadial loess. In relation to loess deposits overseas, interstadial loess is is from a fluvio-glacial source and post-stadial loess is, in the broadest sense, from a continental source.