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The Science of Tufa What Is Travertine Travertine Point A8 Saturday, January 10, 2015 Imperial Valley Press Land of Extremes QUESTIONS? Contact Local Content Editor Richard Montenegro Brown at [email protected] or 760-337-3453. DEPOSITS ARE STILL VISIBLE TODAY Blake’s Sea or Lake Cahuilla? BY NEAL V. HITCH | Special to this Newspaper/Imperial Valley n 1858, Dr. William Blake recoded the shoreline of an ancient lake in the Imperial Valley while completing a rail- road survey. He noted a discoloration of the rock along the western shore at around 40 feet above sea level. He named it Lake Cahuilla, though early writers also called it Blake’s Sea. IAccording to a 1995 article shells. Calcium carbonate is written by Pat Laflin, Con- difficult to dissolve in water. gress authorized a series of In warm water, it reacts with surveys in 1843 to discover a the environment becoming practical railroad route to the increasingly insoluble until it Pacific. precipitates out of the solu- A topographic engineer, tion. named Lt. K.S. Williamson, Under different tempera- led the southern expedition, ture conditions, it naturally and Professor William R. takes the crystalline form of Blake of New York served as calcite or aragonite. geologist. Basically, tiny solid parti- Professor Blake was the cles fall out of the water solu- first to explain the origin of tion and collect on rocks. the Salton Sink. Aragonite is precipitated As the survey party moved when temperatures are hot, from the San Gorgonio Pass and calcite precipitates when to the Coachella Valley, Blake temperatures are cooler. noticed the mark of the an- Scientists are studying the cient sea along the base of impact of small micro bac- the Santa Rosa Mountains. teria, like algae, that may The ancient waterline activate the precipitation mark, measured at 42 feet process. above sea level, is visible at This would explain why many places. He traced the tufa deposits are found along ancient history of the fresh- the shallow edges of Lake Ca- water lake and gave it its huilla where there is plenty name. of access to sunlight. The deposits are still The idea of “precipita- visible today as you tion” seems simple to drive up High- a chemist, one even MAP: Map of Ancient way 86 at the People told me a joke: “if Lake Cahuilla. north end of caught fish you are not part ABOVE and LEFT: the Salton and turtles and of the solution, Archaeological exca- Sea. hunted birds. then you are vations at Travertine They look When the lake part of the pre- Point in 1958. IMPERIAL like a line started to dry the cipitate.” VALLEY DESERT MUSEUM COL- of discolor- But it was LECTIONS people followed FAR LEFT: Tufa on a ation along the receding difficult for a the rocks, historian to grasp rock from Travertine shoreline. IMPERIAL VALLEY DES- and are some- ... when I think Point. times compared of precipitation, I ERT MUSEUM PHOTO BOTTOM: Tufa line that to a bathtub ring. think of rain. The Oxford can be seen from High- Up close the discoloration definition of precipitation is way 86 at the north end looks a little like coral or “to cause (a substance) to be of the Salton Sea. PHOTO some kind of marine growth. deposited in solid form from COURTESY OF MICHAEL FIELD In actuality, the deposits are a solution.” Rain is the atmo- tufa-solids, a form of lime- spheric water vapor that falls stone left behind on the rocks under gravity: it precipitates after the water in the lake — it falls out of the solution. calcium carbonate deposits Italy, where the stone gets its County. evaporated. So in the case of tufa, the cal- known as travertine. name. This marker is both geolog- cium carbonate is like a rock This is a sedimentary lime- Here, the deposits are hun- ical and cultural. It should The science “raining” out of the stone rock. Travertine exists dreds of feet deep. The stone remind us that at one time water. in white, tan, cream-colored, is lighter than granite or Imperial County looked very of tufa All of this and even rusty varieties. marble and is easy to quarry. different and that the lake to say, the It is often formed at the provided a resource to ear- Tufa is lines on mouth of a hot spring or in Travertine Point ly peoples for thousands of formed by the rocks a limestone cave. In caves, it years. the pre- that you can form stalactites and sta- Native Americans migrat- But it should also remind cipita- see along lagmites. ed seasonally between the us that it is not that differ- tion of Highway The most well-known mountains and the lake. ent. The Salton Sea can be calcium 86 are travertine formation in the Campsites and villages were seen as a remnant of the an- carbon- limestone United States is Mammoth located along the shore. Peo- cient lake. ate in deposits Hot Springs in Yellowstone ple caught fish and turtles Driving along Highway 86 ambient created National Park. For centuries and hunted birds. When the offers a view of both, the high tem- by the lake. travertine has been used as a lake started to dry the people water-line formed a thou- perature The most notable de- building material. followed the receding shore- sand years ago and the cur- water bodies. Calcium car- posit line is at a place called From the arches of the Col- line. rent lake formed 100 years bonate is a common chemical Travertine Point. osseum in Rome to the lobby Archaeological sites have ago. All a part of a geological compound found in rocks walls of the Sears Tower in been found between 40 feet process that we see every day. all over the world. It is also What is travertine Chicago, travertine has been above sea level and 203 feet Neal V. Hitch is director of the main component of sea a sought after decorative below sea level. As the lake the Imperial Valley Desert shells, snails, pearls and egg- Geothermally heated hot- limestone, often confused receded it also left its mark Museum in Ocotillo. springs sometimes produce with marble. in the tufa clearly seen on The main source of the western side of travertine has Imperial been Tivoli, .
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