John Hardcastle looks at the Timaru loess: Climatic signals are observed, and fragipans

Abstract

John Hardcastle (1847–1927) made several important loess-related observations in New Zealand in 1889 and 1890. He is best known for his ‘invention’ of loess stratigraphy, his observations of loess as a ‘climate register’, but he made significant contributions in other areas. He outlined the event-sequence approach to loess deposit formation in 1889, well before the better known exposition in 1966. The basic sequence for loess deposit formation P1T1D1T2D2 could well be named the Hardcastle sequence. He pointed out the problem of silt particle production as an important question, emphasizing the role of glacial action, and he drew attention to the occurrence of bird crop stones in loess deposits, as possible markers for deposition stages. Moa stones in particular may give useful information about New Zealand deposits. The Timaru loess, investigated by Hardcastle, has been proposed by J.D.Raeside as the type section for New Zealand loess. JH was probably the first person to describe fragipans (characteristic hard layers) in loess. The fragipan was not properly defined and named until the Guy Smith proposals c.1948, but Hardcastle offered detailed descriptions in 1890.As the site of important loess investigation, and possessing impressive stratigraphy, the Timaru loess could be proposed as an international loess section for New Zealand. Hardcastle's stratigraphic observations were probably among the first relatively sophisticated palaeoclimatological observations made. The INQUA Loess Focus Group could recognize the Timaru Loess (the Dashing Rocks section) as the representative loess section for New Zealand- a reference section for studies of loess stratigraphy and chronology (hopefully preserved and curated by the local government authorities and other interested parties).