...Twice we found rain-water in the Mokoko before we reached Mokokonyani, where the water, generally below ground elsewhere, comes to the surface in a bed of tufa... 
David Livingstone 「Missionary Travels and Researches in South Africa」
... In passing along we see every where the power of vegetation in breaking up the outer crust of tufa...
David Livingstone 「Missionary Travels and Researches in South Africa」
...The calcareous tufa seems to be the most recent rockformed...
David Livingstone 「The Last Journals of David Livingstone, in Central Africa, from 1865 to His Death, Volume II (of 2), 1869-1873」
...It establishes its burrow in a soft tufa, and directs it almost horizontally, hollowing it out in such a way that the axis of the hole makes a very small angle with the soil...
Frédéric Houssay 「The Industries of Animals」
...So thefire and the heat of the flames, coming up hot from far within throughthe fissures, make the soil there light, and the tufa found there isspongy and free from moisture...
Vitruvius 「Ten Books on Architecture」
...It consists of a series ofvaults excavated out of the solid tufa rock, where it slopes down fromthe Capitoline Hill into the Forum, each lined with massive blocks ofred volcanic stone...
Hugh Macmillan 「Roman Mosaics」
...Itwas probably at first a natural spring gushing out of the tufa rock ofthe Palatine Hill, but being dried up, it became in later times alacus or basin artificially supplied with water...
Hugh Macmillan 「Roman Mosaics」
...15 bivouacked on the side of a traphill, among some fine oat-grass growing on calcareous tufa...
A C and F T Gregory 「Journals of Australian Explorations」
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