'Expanse' in the Bible

The shape of an expanse, with a gleam like awe-inspiring crystal, was spread out over the heads of the living creatures.

And under the expanse their wings extended one toward another. Each of them also had two wings covering their bodies.

A voice came from above the expanse over their heads; when they stood still, they lowered their wings.

The shape of a throne with the appearance of sapphire stone was above the expanse. There was a form with the appearance of a human on the throne high above.

Then I looked, and there above the expanse over the heads of the cherubim was something like sapphire stone resembling the shape of a throne that appeared above them.