Peats and woody-detrital deposits at two localities close to the Barnes Ice Cap at approximately 70°N contain insect faunas and mosses that indicate that these sites were situated close to tree line during the period of deposition. Modern tree line occurs some 1325 km (820 mi) to the south and southwest of these sites. Attempts to provide numeric ages based on the U-series of woody fragments were not successful. Although it has been assumed in the past that these peats were laid down during the last interglaciation, the inferred paleoclimatic conditions based on the insect faunas and plant remains suggest a substantially older (possible late Tertiary to mid Quaternary) age. The Flitaway and Isortoq sites probably had an annual average temperature at the time of deposition which was between −8 and −9 °C, i.e., about 4 – 5 °C warmer than today. Such information is important to calibrate and check global climatic models that predict substantial high-latitude greenhouse-gas warming.