[Cob] National Park Service earthbag construction

[Mary Hooper]

snipped:
 the covering made from balls of stabilized earth made and placed one at a
time.

What is stabilized earth?

snipped:
Nader figured the cement often cracks due to expansion and contration.
Especially in the hot desert. The By using the balls he is sort of
predefining where the cracks will be. He then calks the cracks with some
type of lime mix I believe.

Cement? These are cement over earthbag? surely not? The thin vaults are
cement? I may be recalling the wrong photos, but .....
thanks for any clarification...Mary