The Marianas essentially constitute an island chain stretching from longitude 144 to 147 degrees East and latitude 10 to 21 degrees North. They are of volcanic origin and include 16 larger islands covering an area of 1,140 sq. kms. The largest of these is Guam (520 sq. kms) which was ceded by Spain to the United States in 1898. The German colony constituted the rest with an area of about 620 sq. kms and in 1899 a population of 2,500.