To the best of my knowledge, the state park preserves the spectacular tufa towers.
From the sacbee.com
Both the materials, sandstone and tufa, and the models were taken from there.
From the en.wikipedia.org
Later they carved bigger cave homes and churches out of the soft tufa stone.
From the businessweek.com
And for those whose creativity runs to mud pies, there is tufa, also called hypertufa.
From the heraldtribune.com
Two heads made of Aniene tufa from the tomb are now in the Vatican Museums.
From the en.wikipedia.org
Tufa, a porous or cellular variety of travertine, is found near waterfalls.
From the en.wikipedia.org
Tufa forms wherever springs rise to the surface with calcium in the water.
From the en.wikipedia.org
The Smithsonian garden was built with more than 40 tons of gravel as well as tufa stone.
From the washingtonpost.com
The area of a river, in which the formation of tufa occurs, is called precipitation area.
From the en.wikipedia.org
More examples
A soft porous rock consisting of calcium carbonate deposited from springs rich in lime
Tuff: hard volcanic rock composed of compacted volcanic ash
Tufa is a variety of limestone, formed by the precipitation of carbonate minerals from ambient temperature water bodies. Geothermally heated hot-springs sometimes produce similar (but less porous) carbonate deposits known as travertine. ...
A limestone rib formation that protrudes from the wall which can sometimes fit within the pinching grasp of a climber's hand.
Soft volcanic stone, used in making grottos.
Solidified volcanic ash. Also known as tuff.
(soil): A porous, calcareous rock, often found around mineral springs.
A terrestrial carbonate rock with spongy texture, formed around springs, lakes, or along streams. Synonymous with travertine.
A spongy form of calcium carbonate created by evaporation around springs or from a lake surface.