Limburg is a province in Belgium, bordered by the southern part of the netherlands, both are speaking Flemish or Netherlands. The geology is also similar, the hill country is substantially higher than the lowland of the netherlands, the hills consist of limestone which was mined for various reasons. But below the limestone there are also layers of coal, and so both areas, on both sides of the border, have coal mines. Coal-mining started in the 19th century, attracting immigration from other areas, including Mediterranean countries. During the 20th century coal mining was an important industry, but it declinde since the 1970s and finally ended in the early 199s.