Sedimentological, micropalaeontological and organic geochemical (Rock-Eval pyrolysis) criteria suggest that calving glaciers, probably from Antarctica, likely reached the sea and floated by New Zealand during the middle Paleocene, dropping angular coarse detritus into marine mud. The dropstone event coincides with marked shifts in organic geochemistry of the associated marine shale as well as changes in foraminiferal productivity. The implied cool-climate event may have only been a short-term climatic oscillation, perhaps of only thousands of years. However, it was significant enough to have affected the biota and organic matter in the water column. The dropstones may represent a deep-water example of a correlative conformity referred to in sequence stratigraphy literature. Although the dropstones are easily recognizable in the sediments, the interpretation relies on associated palaeontological and organic geochemical data. Sea-level curves presented elsewhere in the literature show mid-Paleocene sea-level falls which approximately coincide with the time when the dropstones in eastern New Zealand were deposited.