Coastal hills descend abruptly to Ionian Sea beaches along the Albanian Riviera from Vlore Bay southward to about Sarande. The 500- and 1,000-foot contour lines are within a mile or so of the water along nearly the entire distance. In the northern portion a 4,000-foot ridge is frequently only two to three miles inland. South of Sarande is another small area of coastal lowlands fronting on the Ionian Sea and separated from the Greek island of Corfu (Kerkira) by a mile-wide channel. Climate and soil conditions permit the cultivation of citrus fruits in this southernmost area of Albania. Central Uplands The central uplands region extends south from the Drin River valley, which marks the southern boundary of the North Albanian Alpine area, to the southern mountains. It is an area of generally lower mountain terrain immediately east of the lowlands. In the north, from the Drin River to the vicinity of Elbasan, it constitutes an area about twenty miles wide. It narrows to practically nothing in the vicinity of Elbasan, then widens into a broader triangular shape with its base against the southern mountains. Earth shifting along the faultline that roughly defines the western edge of the central uplands causes frequent and occasionally severe earthquakes. Major damage occurred over wide areas in 1967 and 1969. Softer rocks predominate in the uplands. The most extensive are flysch, a soft crumbly rock that is usually sandstone but frequently contains shales, sandy limestones, and marl. This type of formation erodes rapidly and is the basis of much of the poor alluvial lowland soil. The ridges of the uplands are extensions of the Dalmatian coastal range that enters Albania from Yugoslavia. Elevations are generally moderate, between 1,000 and 3,000 feet with a few reaching above 5,000 feet. Serpentine Zone Although there are rugged terrain and high points in the central uplands, the first major mountain range inland from the Adriatic is an area of predominantly serpentine rock. The serpentine zone extends nearly the length of the country, from the North Albanian Alps to the Greek border south of Korce, an area 10 to 20 miles wide and over 125 miles in length lying generally between the central uplands and the eastern highlands. At Elbasan, however, it makes nearly direct contact with the coastal plain, and it reaches the eastern border for nearly 50 miles in, and north of, the lake region. Within its zone there are many areas in which sharp limestone and sandstone outcroppings predominate over the serpentine, although the ranges as a whole are characterized by rounded mountain features. The serpentine rock derives its name from its dull green color and often mottled or spotted appearance. It can occur in several states. Iron, nickel, or other metals can substitute in its chemical formula for the more prevalent magnesium and will cause color variations. Eastern Highlands