We would need a large number to hold these off, form a barrier.
Whether this will form an effective barrier, no one knows.
The door still formed a barrier, though force could break it down.
Her past formed a barrier between them that would always be there.
But their trunks were never so close as to form a barrier.
Indeed, the powerful black center formed a perfect barrier against attack.
They might have formed a barrier between him and the monster.
The hills, due to their complexity and position form a barrier between the two countries.
The ground could be made to rise up and form a barrier that prevented them from leaving.
Hills form a natural barrier on its northern and western sides.
