The blue-black fountain-pen marks are rivers. Five of them sprawl from the triple summit of Bundok. Two of the south-going streams combine to make a larger river. A third stream roughly parallels this one. But the man with the black grease pencil has drawn a stout line across the stream with such force that loose curls of black grease can still be seen dangling from the linen. The fountain pen has been used to scratch out a bulge in the river just upstream of this mark. Apparently they want to dam the river and make a pool, or a pond, or a lake; it is difficult to get a sense of scale. It is labeled, LAKE YAMAMOTO .