The geomorphic cell: a basis for studying connectivity.

Any attempt to measure connectivity within a system requires a set of entities to be defined that permit the connectivity among them to be quantified. Here we propose the geomorphic cell as such an entity. We provide a means to identify these cells, define a terminology for describing cell state, and identify the pathways of connections (connecteins) to and from cells. We conceptualize the geomorphic cell as being a three-dimensional body of the geomorphosphere, which is delimited from neighbouring cells and neighbouring spheres by different types of boundary. Vertically, the upper boundary of a geomorphic cell is defined by the atmosphere, while the lower boundary is generally formed by the bedrock layer of the lithosphere. Laterally, geomorphic cells are delimited from neighbouring cells with a change in environmental characteristics that determine hydro-geomorphic boundary conditions (e.g. geology, soils, topography and/or vegetation).