page_title: Mono Lake
section_title: Tufa morphology
hierarchical_section_title: Mono Lake / Tufa towers / Tufa morphology
caption_attribution_description: English: These are original sketches made by Edward S. Dana from his book on Crystallographic Study of the Thinolite of Lake Lahontan.
context_page_description: Mono Lake is a saline soda lake in Mono County, California, formed at least 760,000 years ago as a terminal lake in an endorheic basin. The lack of an outlet causes high levels of salts to accumulate in the lake and make its water alkaline.
  The desert lake has an unusually productive ecosystem based on brine shrimp, which thrive in its waters, and provides critical habitat for two million annual migratory birds that feed on the shrimp and alkali flies. Historically, the native Kutzadika'a people ate the alkali flies' pupae, which live in the shallow waters around the edge of the lake.
  When the city of Los Angeles diverted water from the freshwater streams flowing into the lake, it lowered the lake level, which imperiled the migratory birds. The Mono Lake Committee formed in response and won a legal battle that forced Los Angeles to partially replenish the lake level.
context_section_description: Description of the Mono Lake tufa dates back to the 1880s, when Edward S. Dana and Israel C. Russell made the first systematic descriptions of the Mono Lake tufa. The tufa occurs as "modern" tufa towers. However, there are tufa sections from old shorelines, when the lake levels were higher. These pioneering works in tufa morphology are still referred to by researchers today and were confirmed by James R. Dunn in 1953. The tufa types can roughly be divided into three main categories based on morphology:
  Lithoid tufa - massive and porous with a rock-like appearance
  Dendritic tufa - branching structures that look similar to small shrubs
  Thinolitic tufa - large well-formed crystals of several centimeters
  These tufa types vary interchangeably both between individual tufa towers but also within individual tufa towers. There can be multiple transitions between tufa morphologies within a single tufa tower.
  Through time, many hypotheses were developed regarding the formation of the large thinolite crystals (also referred to as glendonite) in thinolitic tufa. It was relatively clear that the thinolites represented a calcite pseudomorph after some unknown original crystal. However, the original crystal was only determined when the mineral ikaite was discovered in 1963. Ikaite, or hexahydrated CaCO₃, is metastable and only crystallizes at near-freezing temperatures. It is also believed that calcite crystallization inhibitors such as phosphate, magnesium, and organic carbon may aid in the stabilization of ikaite. When heated, ikaite breaks down and becomes replaced by smaller crystals of calcite. In the Ikka Fjord of Greenland, ikaite was also observed to grow in columns similar to the tufa towers of Mono Lake. This has led scientists to believe that thinolitic tufa is an indicator of past climates in Mono Lake because they reflect very cold temperatures.
caption: These are original sketches of thinolite made by Edward S. Dana from his book from 1884: Crystallographic Study of the Thinolite of Lake Lahontan.[9]
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