The seven-day old provides for some very interesting views of a wide variety of formations along the terminator. Perhaps the most prominent are the Alpine Valley and Apennine Mountains which lie on the eastern edge of Mare Imbrium. The Alpine Valley is believed to have been formed about 3.5 billion years ago and represents an area measuring approximately 11 km wide and 130 km long. The rille which lies at the heart of the Alpine Valley and found on the northern portion of the image below (running from southwest to northeast) includes a fault measuring 700 m wide which is visible on evenings of good seeing. The three craters forming a group to the immediate south of the Alpine Valley are Aristillus, Autolycus and Archimedes. Further south from these craters we reach the massive Apennine Mountain range which measures 100 km in width and 950 km in length and reaches an altitude of 5400 meters (or 16400 feet).