Pellicle

Pellicle: Pellicle is Latin for a thin skin and has been adopted to describe parts of mushrooms, photographic film, single-celled organisms, and tooth enamel. Much like ligand (Latin for tie together, bind), this is a scientific-sounding (i.e. Latinate) word that has been adopted by many scientists for their own particular use.

We are acquainted with a mere pellicle of the globe we line on. Many have not delved six feet beneath the surface, nor leaped many above it. - Thoreau

[As Thoreau approached his death,] he was not about to let up on his big projects. ... His Concord calendar, the cultural landscape and interactions of all four seasons of his hometown, his forever explored pellicle of land?