No topography is visible on Mars from Earth-based telescopes. The bright areas and dark markings on pre-spaceflight-era maps of Mars are all albedo features. (See Classical albedo features on Mars.) They have little relation to topography. Dark markings are most distinct in a broad belt from 0° to 40° S latitude. However, the most prominent dark marking, Syrtis Major Planum, is in the northern hemisphere, outside this belt. The classical albedo feature Mare Acidalium (Acidalia Planitia) is another prominent dark area that lies north of the main belt. Bright areas, excluding the polar caps and transient clouds, include Hellas, Tharsis, and Arabia Terra. The bright areas are now known to be locations where fine dust covers the surface. The dark markings represent areas that the wind has swept clean of dust, leaving behind a lag of dark, rocky material. The dark color is consistent with the presence of mafic rocks, such as basalt.