'Mountains' in the Bible

I saw in the night a man on a red horse, between the mountains in the valley, and at his back were horses, red, black, white, and of mixed colours.

And the man who was between the mountains, answering me, said, These are those whom the Lord has sent to go up and down through the earth.

And the man who was between the mountains, answering, said to the angel of the Lord, We have gone up and down through the earth, and all the earth is quiet and at rest.

And I turned, and lifted up mine eyes, and looked, and, behold, there came four chariots out from between two mountains; and the mountains were mountains of brass.

And ye shall flee to the valley of the mountains; for the valley of the mountains shall reach unto Azal: yea, ye shall flee, like as ye fled from before the earthquake in the days of Uzziah king of Judah: and the LORD my God shall come, and all the saints with thee.