The triangles are ruins. The different colours represent ruins from different historical epochs. The red ones are ancient statutes of dragons, now weathered beyond recognition, that used to mark the boundary of an ancient kingdom.
There has recently (about 500 years ago) been a catastrophic flood of biblical proportions. This has altered much of the original geography. The Ashor Sea is largely a flood creation and some of the original watercourses have, as yet not completely eroded away. One of these is the canal which used to form part of a more complex river system, but now forms an extra link with the wider channel between the seas. Those to channels will eventually erode away the area between them turning it into an island.
Torq