In the central nervous system, there are three different layers that cover the spinal cord and brain. These are called the meninges, and their three levels consist of the: pia, arachnoid, and dura mater. Bone is situated above these layers, followed by periosteum (a fibrous membrane that covers bone) and skin.The dura mater is the top layer of the meninges, lying beneath the bone tissue.This material at times opens into sinus cavities (spaces) located around the skull.he dura mater is the top layer of the meninges, lying beneath the bone tissue. This material at times opens into sinus cavities (spaces) located around the skull.
Planet Earth Making Mountains Planet Earth filmmakers came out in the rugged mountains of Nepal in hopes of filming the elusive snow leopard for the Mountains episode. 01:51.
As cited in another answer, there were some episodes where they made it back to Earth, but only temporarily: The first, from Season 1, is Return From Outer Space, where Will is beamed to a small town in Vermont.he second, from Season 3, as pointed out in the other answer, is Visit to a Hostile Planet, where they land on Earth in 1947. (There is never any explanation given about if the Robinsons ever make it back to their own time period.).