A map of the British Isles. Parts are shaded in light brown to show the location of oak population A. This includes regions of Ireland; the west coast of Scotland; north-west England; Wales; Cornwall; north-east England. Dots mark locations of soil cores with and without pollen. Lines drawn largely from east to west show northern extent of the population at different times. These are spaced by 500 years, showing that oaks arrived in the south around 9500 years before the present, and to north Scotland by 6000 years before the present. These lines are solid lines where the data is known with high confidence, dotted with low confidence. These lines are widely spaced in England and southern Scotland, showing extents up to 8000 years before the present. North of this point, they are much more closely spaced. Arrows on the map show routes of dispersal, roughly drawn from south to north. A continuous set of these arrows is labelled in red, from the south of England to north-west Scotland. It starts about halfway between the 9000 and 9500 lines, and finishes on the 6000 line. This line is 7.4 cm long on screen; the scales shown are 1 cm to 100 km (1.6 cm to 100 miles).