Jean Grove's research continued to involve glaciers but increasingly it turned towards a subject, then somewhat neglected, namely historical climatology, following in the footsteps of Gordon Manley and Hubert Lamb. It was known that glaciers in the Alps had extended well beyond their present limits, leaving behind moraines dating from roughly 1600CE to 1900CE, the period known as the 'Little Ice Age'. Jean sought 'proxy' data for the instrumental climatic record in the Alps and elsewhere.