The surface of the vilayet is generally mountainous, except in the central valley of the Maritza, and along the banks of its tributaries, the Tunja, Arda, Ergene, &c. On the west, the great Rhodope range and its outlying ridges extend as far as the Maritza, and attain an altitude of more than 7000 f t.
The interesting little Rhodope veranyii, which has no odontophore, has been associated by systematists both with these simplified Opisthobranchs and with Rhabdocoel Planarians.
(1883); Bohmig, " Zur feineren Anatomic von Rhodope veranyi, Kolliker," Zeitschr.
The most distinguishing features of the country were the chain of Rhodope (Despoto-dagh) and the river Hebrus (Maritza).
The greater part of the country is hilly and irregular, though there are considerable plains; but besides Rhodope two other tolerably definite chains intersect it, one of which descends from Haemus to Adrianople, while the other follows the coast of the Euxine at no great distance inland.
Gumuljina is situated on the river Karaja-Su, south of the eastern extremity of the Rhodope range of mountains and 13 m.
The core is formed by the mountain masses of Rhodope, Belasitza, Perin and Rila; and here Palaeozoic and Mesozoic beds are absent, and the earliest sedimentary deposits belong to the Tertiary period and lie flat upon the crystalline rocks.
The Bulgarian Mahommedans, or Pomaks, who inhabit the valleys of Rhodope and certain districts in northern Bulgaria, are numerically insignificant; the Greek followers of Islam are almost confined to Crete.
In 1886 the informal union of Eastern Rumelia with Bulgaria was sanctioned by Europe, the districts of Tumrush (Rhodope) and Krjali being given back to the sultan.
Penetrating the difficult Rhodope country had carried out a vigorous offensive in several directions, as the result of which Adrianople was invested on the S.W.
Lately operating in the Rhodope came up, some by the Arda and some via Demotika on the S.
On the east of this river, three vast ranges, the Transylvanian Alps, the Balkans and Rhodope, encroach upon Servian soil; while on the west there is a chaos of mountain masses, outliers of the Bosnian and Albanian highlands.