5. Climate arctic. Temp. 8° Cent. Salix polaris.
6. Climate subarctic. Temp. 8°-12°. Younger Dryas period.
7. Temperature moderates. Dry continental climate. a. Aspen Epoch; b. Pine period with oaks beginning to appear=Ancylus period.
8. Moderate insular climate. Temp. 15°-17° Cent. Climatic optimum. Older Tapes layers, Maximum of Littorina depression. Shell-heaps.
9. Temp. 15°-17° Cent. Probably slightly cooler than 8. Oak Epoch. Beech begins to appear but is still rare. Younger Tapes (Dosinia) layers.
10. Moderate insular climate about 16.1° Cent. Beech Epoch. Mya layers.
These climatic changes seem to argue for a comparatively recent date for the Littorina depression and the shell-heaps.