Coverstones, the Iris and Abandoning of Earth by the Goa'uld
[inc. spoiler for back of series 3]
As a result of other threads, and watching series 2&3, I have wondered the following:
When a wormhole is established, incoming or outgoing, it creates a vortex. In "A Hundred Days" the gate is totally buried, yet a vortex is possible. Similarly, apart from what is probably an oversight, the iris is always open in the SGC when the gate is disengaged, but closed after the vortex. It would be much safer to leave it closed until absolutely positive it should be opened, unless in doing so it would be destroyed by the vortex.
Side question: isn't this because it is the event horizon, so there is no point trying to keep the iris a few microns away from it!?
Anyway, if the vortex wipes out anything in its path, how would a simple coverstone keep Ra out? Similarly, even if the gate was buried, he could have returned in his hatak (side question: should hatak be apostrophed?).
So, my discussion point for tonight: after stripping the earth of its most valuable asset, human beings for populating the galaxy as hosts, slaves etc., did Ra and the System Lords simply forget about the planet as a technologically worthless, when the religion aspect of the overlordship wore off?