There are also three mountain ranges, Moka, Grande Port and Black River Mountains. Rodrigues is also composed of basalt and is mountainous with a central region that divides the island from southeast to northwest. The principal rivers are the Grand River South East and the Grand River North West, additionally, some lakes have formed in the volcanic craters. Mauritius has a tropical maritime climate with the SE trade winds prevailing from April to November. Devastating tropical cyclones occur from November to March and rainfall is at its heaviest during this period.
Humidity increases while temperature decreases with altitude.
Other religious minorities include Buddhists, Confucianists, Baha'is and Ahmadiyyahs. Mauritius began to achieve self-government from Britain in the late 1950's and gained complete independence in March 1968. In 1971, amid growing unrest and strikes the government declared a State of Emergency and in Aug. 1971 arrested the MMM's leaders to prevent disruptions occurring when Queen Elizabeth II visited in Mar. 1973. The party formed an alliance with two other political parties creating the Alliance Party which won elections in Aug. 1983. In Dec. 1983 Mauritius became a republic within the Commonwealth and in Dec. 1985 four Alliance Party members were arrested at Amsterdam Airport for carrying heroin.