One of the last canal Maps of Mars, after the space age began.

THE PHYSIOGRAPHY OF THE MARTIAN SURFACE
Approximately 70 per cent of the surface is covered by deserts or continents, which appear to be of reddish-yellow colour. Darker areas, called maria (singular mare) occupy approximately 27 per cent of the
surface. … The remaining portion of the surface is occupied by the polar caps, generally interpreted as being deposits of hoarfrosts (H20 ice or C02 ice). … Other famous markings are the canals, which form a network over the deserts and perhaps also the maria enveloping the whole Martian surface. Intersections of canals are called oases. Fig. 1 shows schematically the location of deserts, maria, canals and oases.

Ronca, L. B. (1970). An introduction to the geology of Mars. Proceedings of the Geologists’ Association, 81(1), 111–128. doi:10.1016/s0016-7878(70)80039-6