ABSTRACT
The name of “Mudland” by which Borneo and especially West-Borneo is known, has little in it to attract the geologist, but so far. I had not been able to judge for myself whether it deserved to be so called. As, however, on the 8th of February 1894, we approached the mouth of the Kapoewas, I realized whence the name must have originated. Mud greets the newcomer far out into the sea. At a distance of 50 kilometres from the land, the clear seawater becomes discoloured by the mud carried out by the Kapoewas, and only very slowly and gradually it mixes with the salt water. The line which separates the salt from the fresh water is very clearly marked, there is a slight ripple on the water and an accumulated mass of vegetable matter and scum. When the water level is high in the rivers, which for the Kapoewas is usually during the months of November, December and January, this line of demarcation extends out as far as Poelau 1 ) Datoe, fully 62 kilometres beyond the mouth of the Kapoewas Kĕtjil.
