The phrase "a boundary beyond which" is correct and usable in written English.
It can be used to describe a limit or threshold that cannot be crossed or exceeded.
Example: "There is a boundary beyond which we cannot go without proper authorization."
Alternatives: "a limit that cannot be crossed" or "a threshold that cannot be exceeded."
On first arriving at his new home, he is given a map of the neighbourhood, on which is marked a boundary beyond which he cannot stray.
The two controversies, together, indicate a boundary beyond which judicial rulings and legislative acts cannot resolve disputes — where we have to live with the disagreeable opinions of fellow citizens.
Dr. Vinge compared that point in history to the singularity at the edge of a black hole: a boundary beyond which the old rules no longer applied, because post-human intelligence and technology would be as unknowable to us as our civilization is to a goldfish.
SAN DIEGO--One of the most famous astronomical predictions of the 20th century was the black hole, a massive object circumscribed by a boundary beyond which nothing can escape.
Yet I argue that what we face first is a "perception singularity": a boundary beyond which events cannot be perceived by the observer.
Structures near the periphery were oversampled because the sampling's primary purpose was to identify a boundary beyond which there were no discernible impacts on indoor air, for mitigation purposes.
The melodic passages have excellent hooks — the "Perfect as it was" aria is insidiously hummable in a Richard Rodgers way — but after a minute or two they seem to run up against an invisible boundary, beyond which the quasi-modernistic devices take over.
The arm is thus considered to form an outer boundary beyond which attention does not spread.
However, even cases where close kin were identified as a constant and close support to the dyad, there appeared to be a clear exclusionary boundary beyond which they did not penetrate.
From his trailer in the town of Rachel, Nev., Mr. Arnu is less than 10 miles from an unmarked military boundary, beyond which the top-secret Air Force base known as Area 51 sits on a dry salt flat guarded by big arid mountains and bleak desert on all sides.
Although Ms. Ledan was on foot and had used a sidewalk, Mr. Zuckerman suggested that the security booth marked a boundary line beyond which someone "could be trespassing".
