Since someone brought Geological time into this, I'll play along.
Start at the top with Eon.
Late 19th Century to Current Day would be the Modern Eon. Pretty much, it's an era where there is some sort of recognized championship and more importantly, some sort of record keeping and recorded documents are present.
To Break it up even further. The Era.
Era is thrown around an awful lot, but in my opinion, there are 3 Era's of the Modern Epoch.
The Pioneer Era
Late 18th Century to Post World War 2.
Guys like Shadow and Gelgarin are far more knowledgeable then I am with this older stuff. You have an era here that establishes some sort of World Champion recognition, and ultimately a transition from Shoot to Kayfabe. I wouldn't know how to further break this era down myself.
The Early Television Era
Late 1940's to Mid 1980's.
Here you have a distinct change from the previous era. Television begins to take off and the establishment of several things occurs. 1. The Territory System. This system takes off, forcing the establishment of the NWA to recognize championships. 2. The NWA championship becomes the undisputed crown jewel in the business.
As I said before, guys like Shadow and Gelgarin could really break this down further.
The Cable Television Era/McMahon Era
Mid 1980's to Current Day.
Vince McMahon essentially changed the business, and I don't think this Era will truly end until McMahon either steps down and away from the WWE, or dies. You can break this Era into Periods, which I think that there are three distinct periods of the Cable Television Era. I'm using the WWF/E to write history. Why? they won the wars with their competition, and the big dog gets to write history. Within Each Period I'll make Epoch's.
The Early Federation Period
1984 - 1994.
Rock N Wrestling
1984 - 1989
I don't really have a name for this Epoch
1989 - 1994
The Monday Night Wars 1994 - 2002
The New Generation 1994 - 1997
The Attitude Era 1997 - 2000
The InVasion 2001 - 2002
Brand Extension 2002 - Current
Ruthless Aggression 2002 - 2005
???? 2005 - 2007
PG Era 2007 - Current
I'll elaborate more on my dates if anyone wants me to.