The determining feature of this is the Pagasaeus Sinus (Gulf of Volo), a landlocked basin, extending from Pagasae at its head to Aphetae at its narrow outlet, where the chain of Pelion, turning at right angles to its axis at the end of Magnesia, throws out a projecting line of broken ridges, while on the opposite side rise the heights of Othrys.
It forms an irregular square, extending for about sixty miles in each direction, and this area, which is for the most part level, is enclosed by well-marked boundaries - by the Cambunian Mountains on the north, and by Othrys on the south, while on its western side runs the massive chain of Pindus, which is the backbone of this part of Greece, and towards the east Ossa and Pelion stand in a continuous line; at the north-eastern angle is Olympus, the keystone of the whole mountain system.
The elevation of some of the summits in these ranges is considerable, for three of the peaks of Pindus are over 5000 ft., and Olympus, Ossa and Pelion reach respectively the height of 9790, 6398 and 5350 ft.
The principal of these were called Upper and Lower Thessaly, the former comprising the western and south-western part, which contains the higher course of the Peneius and all those of its tributaries that flow from the south - the Enipeus, the Apidanus, the Onochonus and the Pamisus; while the latter, which reaches eastward to the foot of Ossa and Pelion, is inundated in parts at certain seasons of the year by the Peneius, the flood-water from which forms the lake Nessonis, and, when that is full, escapes again and pours itself into the lake of Boebe.
PELION, a wooded mountain in Thessaly in the district of Magnesia, between Volo and the east coast.