A treeline is not one phenomenon. It is wherever a particular limiting factor becomes severe enough, and the factor differs entirely between a mountain, a bog, a coast and a…
There is an old puzzle about a ship whose planks are replaced one at a time until none of the original timber remains, and the question of whether it is…
The question worth asking at any waterfall is what makes the drop possible, because a river will otherwise smooth its own bed given enough time. Something is preventing that, and…
The first question at any boundary is what it is made of, because that was decided entirely by what was to hand. The second is what shape it is, which…
The useful habit is to ask what each feature is for rather than what it looks like. Nearly every one addresses a specific difficulty, and several address problems that are…
The defining property is that nothing here is constant. Salinity at any given point changes twice a day and again with the seasons, and every organism and process in an…