Mono Lake :: Biology Science Papers

Mono Lake 1. Mono Lake Mono Lake is a unique body of water lying in the Eastern Sierra Nevadas. For decades its water sources were tapped by the Los Angeles Department of Water and Power (DWP) to use for farming because the lake's high elevation would allow them to easily transport the water to the city and because the water was so saline, people believed it was worthless. The normal traits by which people judge lakes were lacking in Mono: fish could not survive in the salty water, the water was harsh to swim in because of the chemicals and salinity, the scenery was unlike other lakes because there were no trees. Mono Lake appeared to be an isolated lake in the middle of the desert, which DWP could use as they wished. What they hadn't known at the time was the rich history of the lake and the important place it held in the biological world. The geological history of the Western United States has shaped Mono and given it the properties it has, while those properties have given it a specific role in the migration of birds. Plate Tectonics The geological processes that formed and continue to influence Mono Lake began approximately 215 million years ago when the Farallon sea floor plate began subducting, or pushing, under the North American plate. The North American plate was pushed over the sea floor plate by the force of the African and South American plates rifting apart. The friction from the North American plate rubbing against the Farallon plate melted some of the continental rocks, which then erupted in a long volcano chain, the Sierran Arc, stretching from Alaska to Mexico inland from the coast. Over time, the unerupted magma chambers from the Sierran Arc cooled into the granitic batholith that is the Sierra Nevadas (Tierney, 26-27). 2. Diagram of Subduction Zone About 20 million years ago the last part of the Farallon sea floor plate subducted under the North American plate. This put the North American plate and the Pacific plate into contact, but unlike the Farallon sea floor plate, the Pacific plate sheared against the side of the North American plate. Because there was no plate subducting, the North American plate was in direct contact with the mantle (Tierney, 29). Heat from the mantle made the continental crust more ductile, which allowed the crust to extend and thin.