 Ruisdael's work from c. 1646 to the early 1650s, when he was living in Haarlem, is characterised by simple motifs and careful and laborious study of nature: dunes, woods, and atmospheric effects. By applying heavier paint than his predecessors, Ruisdael gave his foliage a rich quality, conveying a sense of sap flowing through branches and leaves. His accurate rendering of trees was unprecedented at the time: the genera of his trees are the first to be unequivocally recognisable by modern-day botanists. His early sketches introduce motifs that would return in all his work: a sense of spaciousness and luminosity, and an airy atmosphere achieved through pointillist-like touches of chalk. Most of his thirty black chalk sketches that survive date from this period.
