This Time It IS A Hole

This one is a hole, rather than a cavern -- it is only 13x7 blocks, but it goes down from the upper hillside down to bedrock.

...and at the bottom, I've encased the lava formation in glass.

Again, it didn't take nearly as long to dig as I'd thought it would. Maybe I should dig a more ambitious hole next time. Or a more ambitious cavern?