There is no "valid scriptural description of the end of the great tribulation" just like there isn't a direct scriptural reference to the event itself described in Matt, Luke, and Mark as being the 70 AD fall of Jerusalem; but the historical record recorded primarily by Josephus clearly is that event. You seem to accept the one but not the other. If you accept what's described in the scriptures of Matthew, Luke, and Mark as the 70 AD fall of Jerusalem which is NOT specifically defined as such in the scriptures, then you should logically look for the answer to its end likewise, which is not in the scriptures, but also can be found in the Josephus historical record. The 70 AD fall of Jerusalem did end; if that was the great tribulation of Matthew, Luke, and Mark, which it is, then it ended. How did it not? That conclusion makes no sense.
We know from history that Matthew 24:15-22 / Mark 13:14-20 / Luke 21:20-24 is referring to the events of circa 70 A.D. - and marks the beginning of the 'great tribulation' that Jesus referred to as stated in Matthew 24:21. (with parallel statements in Mark and Luke)
My focus is not on the fall of Jerusalem; rather, it is on the 'great tribulation' that Jesus referred to.
What scripture says about the end of that [very same] 'great tribulation' is found in Matthew 24:29 / Mark 13:24-25 / Luke 21:25-26.
Then - next - the Second Coming - in Matthew 24:30 / Mark 13:26 / Luke 21:27.
Then - next - the Rapture - in Matthew 24:31 / Mark 13:27 - and, a timing related reference in Luke 21:28.
Please see:
http://mywebsite.us/BibleStudy/Olivet_Discourse.html