Cockatoo Island is the largest of several islands that were originally heavily timbered sandstone knolls. Oak forests were timbered for building supplies and additional agricultural land. The most common sort of buildings would have been roundhouses and rectangular timbered halls. Alsace is the region with the most timbered houses in France. The narrow streets contain some good examples of timbered housing. The area was originally heavily timbered. The removal of timbered houses as part of this renewal was later regretted. The roof was closely timbered, then covered by strips of Malthoid paper.