Hi there!

The back of this bench acts as retaining wall for the patio. The yard drops off right behind it...hard to see in this photo, but if you look at other photos of this house, you will see what I mean. So it is built of concrete masonry units, reinforced with steel and concrete...and then a veneer of Texas limestone. Both textures of stone are limestone, just a different cut.

is this gas??

This is strictly fire burning. I have done projects where we have run a gas line to the fire pit as a starter though.