Alright, so let's see if this is an improvement. Here, for ref, is Michael's original:
There are three major periods shown here, spanning well over a century:
(items that are shades of pink) -- This is known as the Antonine Fort or Stone Fort I. It ran around AD 180 to AD 200, and was sited more or less in the location of the latest fort (the one whose walls are visible today).
* VI-A-1 is a wall foundation running north-south, most likely a barrack.
* VI-A-2 is a road surface. Can't tell exactly what it's doing, as later stonework is on top of it. But it may be part of the so-called "intervallum road" that ran around the inside of Stone Fort I's fort walls.
* VI-A-3 is a well-laid stone drain that was set into some of the VI-A-2 road surface and runs north-south.
(one item - the blue circle) -- This is the very short-lived Severan period (about AD 205 to AD 213).
* VI-B-1 is a small "roundhouse" -- one of dozens that were built in neat rows across the old fort platform in this period. Their use is still debated.
(items in yellow) -- This is Stone Fort II, the fort built by the IV Cohort of Gauls, who occupied Vindolanda from AD 213 until at least about AD 369.
* VII-1 is the grand flagged roadway from the fort's main entrance (the northern entrance) all the way to the HQ.
* VII-2 is a barrack block, one of three located in the NW quadrant of the fort (the other two were dug in '09, and make up the bulk of the stones visible to the right in this picture)
What's important to keep in mind is that all three of these periods are -totally- independent of each other. At the end of the Antonine period, the fort was knocked down -- leveled to the ground -- to make a smooth platform for the Severan roundhouses. After less than a decade, all of the Severan roundhouses were themselves knocked to the ground and the site leveled to build Stone Fort II.
Oh, and for a last orientation, here's a plan of where the pic is taken from: