Tuesday, March 19, 2024

Drunk on Geomorphology - Salt Flats Slipstream IPA


The next Drunk on Geology is for Salt Flats Slipstream Indian Pale Ale from the Salt Flats Brewing Company out of Salt Lake City, UT. 

For this post we'll focus on the name of the Brewing Company, Salt Flats. The Salt Flats Brewing Company from Salt Lake City is named after the nearby Bonneville Salt Flats, a large flat pan covered with a hard salt crust which lies to the west of the Great Salt Lake. 

The Bonneville Salt Flats

Although used as a race track in the dry season, the Bonneville Salt Flats have an extensive geological history. The formation of the salt flats started when this region of North America, known as the Basin and Range Province, started to form. At one point in time the western edge of North America was being compressed by the Farallon Plate pushing up against North America, squeezing the continent as the Farallon plate subducted (went beneath) North America.

Graphic of the Farallon Plate subducting beneath North America. Image courtesy of the NPS.

Eventually most of the Farallon Plate was entirely subducted beneath North America, especially along the Californian coast, and the compression was released. This essentially allowed North America to expand outwards, like a squeezed sponge being let go. This expansion thinned the crust, while also producing a series of linear mountain ranges and valleys. 

Graphic of the Basin And Range expansion producing linear mountains and valleys. Image courtesy of ISU.edu

As the expansion progressed, the crust was broken up into a series of smaller blocks. These blocks rotated as the crust stretched out. The rotation of the blocks produced the mountains along the upper corners, with gaps along the lower corners. These gaps eventually were filled with sediment eroded off the mountains, forming the valleys between the mountain ranged. 

Coverage of the Great Basin. Image courtesy of the NPS.

With the thinning of the crust, this area also ended up being lower than the surrounding regions. Because of this, water was not able to flow out of the Basin and Range Province, also known as the Great Basin. Unlike water along the eastern portion of the country and along the west coast, water within the Great Basin does not reach the oceans. All precipitation here eventually ends up in end- or terminal basins, such as the Great Salt Lake, where the only water outflow is through evaporation.

Where the Desert Meets the Mountains

The Great Basin currently contains many end-basins with the primary basin being the Bonneville Basin, which ends at the Great Salt Lake currently. However, during the last ice age the Great Salt Lake was much, MUCH, bigger. Referred to as Lake Bonneville, the lake covered most of western Utah as seen in the map below. 

Maximum extent of Lake Bonneville. Image courtesy of the Utah Geological Survey

Lake Bonneville started to form 30,000 years ago during the last Ice Age and reached its peak at 18,000 years ago. At that point it had reached it's physical maximum volume and started to overflow the glacial moraine dam that was located to the north at Red Rock Pass in Idaho. Once the water reached this level it spilled out over the top of Red Rock Pass. This spillage eventually caused the dam to collapse releasing a mega-flood on to the Snake River Plain. This mega-flood caused to lake level to drop by almost half within a matter of weeks. As the Earth slowly moved out of the Ice Age, the climate started to dry. This drying caused less precipitation within the basin and over time the water level dropped from the imbalance between precipitation and evaporation in the Great Basin. 

As the water in Lake Bonneville evaporated, salt that was dissolved in the fresh water lake started to concentrate. Each year several million tons of dissolved salts are added to Great Salt Lake basin from its tributary rivers. Most lakes worldwide have an outlet and therefore salts and other erodes chemicals don't concentrate within those lakes, being washed out as the water cycles through. However, in terminal lakes while the water is able to evaporate away, the salt is left behind, increasing the salt concentration year over year. 

Where the finish line meets hoppiness

After the water level of Lake Bonneville (which turned into the Great Salt Lake) dropped below the elevation of the Great Salt Lake desert, the Bonneville Salt Flats started to be born. Over time the salty groundwater wicked its way up to the surface, evaporated, and left the salt behind creating a thin crust of salt across the surface of the salt flats. Over time this thin layer of salt built up into a significant hard pan. In places the salt reaches several feet thick in the center of the salt flats and peters out towards the edges. Today these evaporative processes are help along by the addition of salt brine added to the salt flats from the nearby potash operations to prevent the too much salt from being removed from the area through industrial collection lakes. 

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