The River

For an earth scientist, making a river cross-section is not that difficult. You just cross the river and 'section' it (measure the height relative to some line of reference, preferably a horizontal line of reference.) But, and this is where this post get's interesting, what if I told you the water in the river - and any stagnant pools of water around the river - are filled with a rather small but rather deadly parasite?
Finally, all those hours playing "the floor is made of lava" as a kid and "the floor is made of Pahoehoe" as a student paid off. I hope. I guess we'll know for certain in 4 to 6 weeks.