[1] Mariner 7, frame 118 - Mariner 7 near encounter picture 25 is the first of a series of three wide-angle and one narrow-angle view of the Hellespontus and Hellas regions. The cratered region covering most of the picture to the west (right) is the dark Hellespontus. An apparent escarpment to the east forms the boundary of the light region Hellas. The area covered by this wide-angle frame is approximately 450 by 600 statute miles. The picture was taken using a blue filter. Large scale variations in surface brightness have been suppressed by the camera system and will be restored by computer processing of the data. The TV experiment team is headed by R.B. Leighton of Caltech.
From NASA caption.

[2] This photo was taken on July 25, 1976, by the first Viking Orbiter 1 of Phobos showing the cratered side of the Mars satellite that was not viewed by the Mariner 9. North is at the top of the picture and at the lower left of the image is the side of Phobos that always points towards Mars. The large crater near the North pole is approximately 5 kilometres (3 miles) across. The diameter of Phobos viewed from this angle is about 22 kilometres (14 miles).
From NASA caption.

[3] Mariner 6 – 72 - This narrow-angle photograph lies within one of the bright areas of Mars (Deucalionis Regio) and shows in greater detail part of the larger region covered by wide-angle photos 19 and 21. The sharp outlines and apparent freshness of many of the craters on this photograph are particularly striking. However, near the centre-left margin are faint outlines of an older and larger crater with suggestions of a double concentric form which is seen in some craters on the backside of the moon. On the original photo copy, many well-formed, very small craters not much more than 1000 feet across are visible. It is reasonable inference that a still greater number of even smaller craters pock the surface of Mars. The fresh crater, less than 3 miles in diameter, above the centre of this picture, lies in the midst of irregular bumpy terrain which may represent sheets of rocky debris thrown out of this and neighbouring craters or perhaps some nearby still larger crater not visible on this photo. Similar bumpy terrain occurs in the upper right corner, and around some of the other craters. Faintly discernible and running roughly northward through the right side of this photo is an irregularly sinuous ridge strongly reminiscent of “crinkle ridges” seen on the lunar surface. The sun angle for this photo is relatively low (late afternoon on Mars) and the dark areas inside some of the sharp fresh craters are almost certainly shadows. This is strongly suggested by the kidney shape of the darkest area within the largest of the fresh craters toward top of photo. If this initial interpretation stands up, these will be the first definitely recognised shadows cast by topographic features on Mars.
From NASA caption.

[4] Mariner 9 – Mountain near Nodus Gordii (the Gordian Knot). This seventy-five mile diameter Martian crater near Nodus Gordii was photographed by Mariner 9 on November 28. The crater and its immediate surrounding are high ground, emerging island-like from a sea of wind-blown dust. In pictures taken 48 hours later, the edge of the dust cloud had shifted, obscuring the ridges and valleys on the outer northwest rim. Whether the pictures show a smooth crater floor or obscuring wind-blown dust remains to be learned. The multiple concentric fractures on the western rim and the abundant rimless craterlets suggest that this is a caldera or volcanic collapse crater, one equal in size to the largest on the Earth or on the Moon.
From NASA caption.