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Tufa columns at Mono Lake, California. Tufa is a variety of limestone formed when carbonate minerals precipitate out of water in unheated rivers or lakes. Geothermally heated hot springs sometimes produce similar (but less porous) carbonate deposits, which are known as travertine or thermogene travertine.
The soft stone is easily carved and is not degraded by heating. The slick surface of soapstone allows the finished object to be easily removed. Welders and fabricators use soapstone as a marker due to its resistance to heat; it remains visible when heat is applied. It has also been used for many years by seamstresses, carpenters, and other ...
Downspouts are usually vertical and usually extend down to ground level, although may be routed at an angle to avoid architectural features and may discharge onto an intermediate roof. At the bottom of downspout there are typically features to divert discharged water away from the building's foundations to prevent water damage.
A pyroclastic rock containing 25–75% volcanic bombs and/or volcanic blocks is called tuff breccia. [4] Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. [5] Tuff is a relatively soft rock, so it has been used for construction since ancient times. [6]
Copper Leader Head at Penn's Quadrangle, Philadelphia 1894 Copper Leader at Shofuso Japanese House and Garden in Philadelphia. The purpose of a leader head is to help transfer excess water from the roof onto downspouts, thus preventing the gutters from overflowing and water washing over the walls, which is a common occurrence in areas susceptible to heavy rain cycles.
A bedrock mortar (BRM) is an anthropogenic circular depression in a rock outcrop or naturally occurring slab, used by people in the past for grinding of grain, acorns or other food products. [1] There are often a cluster of a considerable number of such holes in proximity indicating that people gathered in groups to conduct food grinding in ...
Puddingstone, also known as either pudding stone or plum-pudding stone, is a popular name applied to a type of conglomerate that consists of distinctly rounded pebbles whose colours contrast sharply with the colour of the finer-grained, often sandy, matrix or cement surrounding them.
A speleothem (/ ˈ s p iː l i ə θ ɛ m /; from Ancient Greek σπήλαιον (spḗlaion) 'cave' and θέμα (théma) 'deposit') is a geological formation made by mineral deposits that accumulate over time in natural caves. [1]