Friday, March 5, 2021

Drunk on Seismology - Tectonic Event Imperial IPA


My next Drunk on Geology is for the Tectonic Event Imperial IPA by Great Basin Brewing Company, makers of the also geologically themed beer Ichthyosaur "Icky" IPA.

What is a "Tectonic Event"? Lets look at some of the definitions of the words to get a better feel for the usage of those terms.

"A branch of geology dealing with the broad architecture of the outer part of the earth, that is, the major structural or deformational features and their relations, origin, and historical evolution."
"A non-committal term for any incident of probable tectonic significance that is suggested by geologic evidence but whose full implications are unknown. Seismic Event."
Seismic Event:
"An earthquake of a somewhat similar transient earth motion caused by an explosion."

Definitions courtesy of the Dictionary of Geological Terms, 3rd Ed. 

So clearly the usage of the term "Tectonic Event" is meant to illustrate an earthquake. Tectonic, specifically Plate Tectonics, is the study of the earth's crust as it is broken up into individual plates. These individual plates move around, slide past each other, move over and under each other, and pull away from each other. Where one plate come in contact with other plates, where these motions occur, this is where the "tectonic events" occur. This is the source of earthquakes, generally.

Plate Tectonic map of the earth. Image courtesy of the NPS

When looking at the plate boundaries in the map above and comparing them to the earthquake locations in the map below, you can see a strong similarity to the locations of these events. And in actuality, the locations of the earthquakes on maps, such as the one below, helped scientists to draw the plate boundaries on the one above. 

Map indicating the locations of earthquakes across the globe. Image courtesy of the NSF.

The plate boundaries are made up of faults. Faults are breaks, or fractures, in the the rocks and they don't just occur at plate boundaries, however the pressures that move the plates are more readily present at the plate boundaries. Earthquakes occur at these plate boundaries because as the plates move past each other the slippage isn't usually smooth.  They get stuck due to friction. However, the pressure that pushes the plates continues. So that pressure builds up over time. The longer the plates are not able to move past each other the more pressure builds up, until the friction holding the plates in place breaks and the plates have a sudden movement. This movement releases the pressure, and the energy, that had built up along the fault. The energy then radiates outwards from the fault slippage, producing the ground shaking known as an earthquake. It is this slippage that would be termed the "Tectonic Event".

Text from the side of the bottle:
"This West Coast-style IIPA features seismically bold flavors with epic momentum and magnitude. A delightfully clean malt profile gives way to powerful quakes of Columbus, Chinook, Citra, Centennial, and Amarillo hops."
One of the ways that seismologists record and study earthquakes are by studying the energy that is released during these tectonic events. This energy is recorded by a machine known as a seismograph, recording a sheet of squiggly lines known as a seismogram. 

An illustration of a seismogram

As the ground shakes, the seismograph records that shaking on a piece of paper (or digitally). Originally this was recorded by simply a pen that would remain free of the earth's motions while the paper would move around beneath it, creating these jagged lines that eventually smoothed out. This image of a seismograph is what is represented on the front of the bottle, surrounding the hops illustration. These graphs, combined with other seismograms from around the world, can be used to identify the exact location of the earthquake, how big the earthquake was (magnitude), and how much energy was released when the fault slipped. 

"Rock your palate to its core"

The reason that the Great Basin Brewing Company chose to honor the tectonic event as one of their logos is likely due to the very seismically active area that their brewery in Reno, Nevada sits within, the Great Basin. 

Map of the Great Basin, showing the north-south trending mountain ranges. Image courtesy of Wikipedia

The Great Basin is an area of the US that is experiencing expansion, kind of like a sponge that had been squeezed and then was let go. As the plate expands, the faults along the Great Basin periodically move because of the stresses placed on the plate due to this expansion. The expansion had produced the topography that can be seen in the image above. This area is covered with north-south trending mountain ranges, which all align with north-south trending fault lines. As the basin continues to expand, periodically these stresses from the expansion will produce earthquakes from the slippage along those faults all over the Great Basin region, including Reno, Nevada, which lies along the western edge of the basin.

Friday, February 26, 2021

Drunk on Geomorphology - Continental Divide Cabernet Franc


The next Drunk on Geology is for Continental Divide Cabernet Franc from the Continental Divide Winery in Fairplay, CO. 

The continental divide is essentially a line that divides the direction that water, specifically in the form a precipitation (rain, snow, sleet, etc.), travels along a continent. All continents have a continental divide. Within North America, that divide travels down the western portion of the country dividing water that flows towards the Atlantic Ocean from water that travels towards the Pacific Ocean.

Simplified Continental Divide of North America. Image courtesy of National Geographic.

This primary continental divide, or Great Divide, runs north to south through several states within the contiguous United States including Montana, Idaho, Wyoming, Colorado, and New Mexico. Since this dividing line is typically along mountain ridges, the line runs through a large number of National Parks as well. 

Continental Divide in Yellowstone National Park in Wyoming

Although the signs typically mark the locations of the continental divides, they aren't always in precisely the correct location, as is the case for this one in Yellowstone. Although I wanted to get out and show water flowing in two different directions, the actual divide was a bit up the slope behind the photographer (my lovely wife), so the water actually just ran down the same side of the sign (as you can see by the stream on the righthand side of the sign).

Continental Divide in Rocky Mountain National Park in Colorado

This sign in Rocky Mountain National Park is probably a bit more accurate than the above sign in Yellowstone. 

The reason that the Continental Divide generally runs along the length of Rocky Mountains is because of the topography of these mountains is generally higher than the rest of the country, dividing the water paths into two different regions. Everything on the eastern half of the Rockies and beyond flows eventually towards the Atlantic Ocean, while everything on the western half of the Rockies flows eventually towards the Pacific Ocean. Well, kind of. Like I mentioned above, the line down the Rocky Mountains is a "simplified" version of the continental divide. It is actually a bit more complicated than that. 

A bit more complicated map of the continental divide system for North America. Image courtesy of Geography Realm

One of the reasons that the true continental divide is a bit more complicated is that North America is surrounded by a few major bodies of water. On the eastern half of the country, although many of those water bodies eventually drain out to the Atlantic Ocean, there are some stops along the way. So the eastern half can be divided up into the directly into the Atlantic Ocean portion, the Gulf of Mexico divide, the St. Lawrence Seaway divide, the Hudson Bay divide, and the Arctic Ocean divide. 

Along the western half of the country most of the land area travels directly into the Pacific Ocean, except for a large landmass in the center of the west called the Great Basin. This region is actually an enclosed basin where water does not exit out of except through evaporation. The largest body of water in the region is the Great Salt Lake, which is salty precisely because water only leaves through evaporation, leaving behind all the salt and other minerals that the streams collect along the way. The Great Basin is actually comprised of many smaller basins with several end lakes, besides just the Great Salt Lake. 

There are also more instances of enclosed end basins and a few can be seen along the central Great Divide, like in Wyoming. Like the Great Basin, there is a section of Wyoming known as the Great Divide Basin, where water also doesn't leave except through evaporation. 

Text on the back of the bottle:
"Nestled high in the Rocky Mountains, we produce and cellar premium wines above 10,000 feet elevation using Colorado grapes. Our scientific approach and meticulous attention to detail ensure exceptional wines crafted to artfully reflect the terroir of Colorado. 
Our Colorado wines are produced from premium fruit from the Grand Valley AVA where the pristine waters from the Colorado mountains irrigate and nourish the vines. Our extreme elevation and cool temperatures help to produce a classic, old world style wine."

And the winery is definitely true to its name. The Continental Divide Winery, actually sits within the shadow of the Great Continental Divide as it winds its way through Colorado. The artist rendition of the mountains on the bottles of the winery I would assume represent the mountains in the background of their winery, through which the divide runs. 

Friday, January 29, 2021

Drunk on Paleontology - Madonna Estate Dolcetto


The next Drunk on Geology is for the Madonna Estate Dolcetto by the Madonna Estate Winery from Napa, California. 

This Drunk on Geology is a little different because the geological nature of the wine is not in the name, or the label, but in the logo of the Madonna Estate Winery itself. 

The logo, as seen here a little better, is what is known as Fermat's spiral. 

Fermat's Spiral. Image courtesy of

Here are a couple of clearer shots of the logo. 

On the front of the bottle.

And on the bottle cork cover. 

Now the reason that I am enamored with the logo, is that this is the same design that my favorite trace fossil, Spirorhaphe, makes. A trace fossil is a fossil that is left behind by the behavior of an organism, like a footprint or a worm burrow, but not a fossil of the actual organism itself. Trace fossils are also named based on their morphology, similar to animals. Spirorhaphe, in particular, is a trace fossil that is part of a group of trace fossils known as graphoglyptids. These fossils form as open burrows, often in deep water at the bottom of the ocean. 

Graphic of graphoglytid preservation. Image courtesy of my dissertation.

These open burrow systems often have intricate patterns to them. They are preserved when a turbidite, which is essentially an underwater landslide, comes down on top of where the graphoglytid burrows are located. The turbidite churns up the water and removes the top layer of sediment over the burrow. The turbidite then deposits the sand and mud that was transported on top of the bottom half of the open burrows creating a cast of the burrows, preserving the intricate burrow system.

Images of some common graphoglyptids. A) Cosmorhaphe. B) Helminthorhaphe. C) Megagrapton. D) Paleodictyon. E) Spirorhaphe. F) Urohelminthoida

Above is an example of some of the varied shapes that come from this group. Scientists aren't sure what the animals that lived in the burrows were doing but the thoughts range from filtering their food out of the sediment, to growing bacteria on the walls to eat, to trapping organisms within the burrow walls and eating those. The one that interests me the most in this instance is Spirorhaphe, which has the same design as the logo!

Example of Spirorhaphe from the Late Cretaceous of Tanzania. 

Initially named in 1895 by Fuchs, Spirorhaphe is an ichnogenus (a genus of a trace fossil) that has gone through a rather tortuous history with many ichnospecies (a species of a trace fossil) being attributed to it and then those definitions changing. Currently, there are three species associated with Spirorhaphe, however even those are contentious in the scientific community. 

Regardless, Spirorhaphe is a fantastic trace fossil and my favorite to boot. 

Text on the back of the bottle:
"Like the cave drawings of Lascaux, Madonna Estate's label represents a history of generations - four generations - that have grown grapes and produced varietal wines with rich concentrated flavors. The continuity of our spiral symbolizes an ongoing commitment to create fine wines."

Tuesday, January 26, 2021

Drunk on Mineralogy - Lucky Rock Pinot Noir


The next Drunk on Geology is for Lucky Rock Pinot Noir from the Lucky Rock Wine Co.

A "Lucky Rock" is gold or a rock containing gold, as mentioned on the Lucky Rock Wine Co.'s website. The chemical symbol for gold is Au, and gold is one of the unique minerals that, in its pure form, is composed entirely of one element. It has a hardness of 2.5 to 3 on the Mohs hardness scale meaning that it actually is very soft (your fingernail is 2.5). For this reason most gold jewelry is mixed with another metal to prevent scratching and bending easily. The karat rating of the gold represents it's purity, where 24 karat is 99.9% pure, 22 karat 91.7%, 18 karat 75%, and so on. Gold naturally does not corrode or tarnish, so even when it is mixed with other metals it usually has a resistance to tarnishing, enhancing its value for jewelry. When gold is found in place, the highest grade of gold is often found in association with quartz veins. Currently gold is considered one of the most valuable metals on Earth, being used as the standard for most money (gold standard).

Lucky Rock logo description from the Luck Rock Wine Co Website.

Gold is often formed initially in relation to volcanic regions, where fluids associated with volcanoes carry the heavy metals up towards the surface and deposit them in rocks. These are found in areas of current or former subduction zones, places where two plates came together forcing one place down and melting it, while the other plate is forced upwards into mountains. Afterwards, erosion will take the gold out of the mountains and carry them down stream. However, since gold is so dense it does not travel easily down rivers and will often settle to the bottom of the river within the rocks and mud within the river sediment. These gold deposits are known as placer deposits and are the primary place where gold panners find gold. They can then use the locations of these placer deposits to backtrack to the original sources of the gold within the streams.

The website also mentions that "Lucky Rock Wine Co., (is) named after one of the more memorable mines they grew up at." So I decided to send them a message to see if I could find out a little more information. This is what one of the owners of Lucky Rock sent back:
"My dad started prospecting and mining in the early 80's in Siskiyou County. He and a partner filed claims for two mines in the Klamath National Forest around 1984 - the hard rock mine was called Lucky Rock. In addition, my dad and a partner sourced funding for their mining efforts and eventually had several investors from Southern California. The company was named Lucky Rock Mining Company and operated for a few years. The "Lucky Rock" mine was just outside Seiad Valley."
Text from the back of the bottle:
"We grew up in a mining family, digging through the soil for a "Lucky Rock." Now our search has turned to discovering California's lucky vineyards from which we craft this tasty Pinot Noir."
With this information I was easily able to find the Lucky Rock mining claims.

Lucky Rock Mining Co mining claims. Map and information from The Diggings.

And as usual, let's take a look at the geologic map of that region, just to get a handle of what we are looking at.

Geologic map of the Seiad Valley region. Map courtesy of the NGMDB

The dominant geological features of this region are by far the Slinkard Pluton, identified as unit Mzd, and the blue unit listed as MzPz towards the north of that. On that specific map Mzd is identified as Dioritic Plutonic rocks and MzPz is some Mesozoic and Paleozoic undifferentiated metamorphoric basement rocks. The Slinkard Pluton however is the major producer of the gold identified within the region. A pluton is a igneous body that formed from the cooling of a body of magma below the Earth's surface. 

Diagram of a subduction zone. Image courtesy of the NPS.

Off the west coast of northern California, as well as Oregon and Washington, is what is known as a subduction zone. In a subduction zone one plate goes beneath the other. As the one plate sinks down, it starts to heat up and melt. That melted plate then rises up and forms a line of volcanoes.

Plates along the northwestern coast of North America. Image courtesy of the NPS.

Along the western edge of northern California is the subduction of the Gorda Plate, which is the remnant of the much larger Farallon Plate that used to be subduction along the entire Californian coast. 162 million years ago, during the Late Jurassic, the melted portions of the Gorda Plate produced the Slinkard Pluton as well as the related Wooley Creek batholith (which is a much larger pluton). 

As the magma body was cooling, the heat from the magma also heated up the surrounding groundwater. This groundwater, as it was heated rose to the surface, cooled, and descended back down to the magma body, creating a cycle. As the hydrothermal fluids moved from the magma towards the surface and through the surrounding rocks, they moved the heavy metals (such as gold, copper, silver, etc.) from within the magma and redeposit them within the surrounding landscape. Over time the gold would weather out of the surrounding landscape and get transported within neighboring streams and rivers. But due to the density of gold, it would often sit at the bottom of streams until a strong enough current came along to move it further along. These deposits, known as placer deposits, are what the Lucky Rock Mining Co. was searching for.

Wednesday, January 20, 2021

Drunk on Petrology - Rockpile Zinfandel


The next Drunk on Geology is for Rockpile Zinfandel from Mauritson Wines

The name of Rockpile is the same as the region in which the vineyards are located. The Rockpile region was a recent AVA denoted in 2002. According to the TTB, an AVA is an American Viticultural Area which is:
"delimited grape-growing region with specific geographic or climatic features that distinguish it from the surrounding regions and affect how grapes are grown."

The specifics of the Rockpile AVA are that it is the northern extent of the Dry Creek Valley AVA that encompasses the areas from 800 to 2,000 feet in elevation with steep, rocky slopes and rocky loam/ clay-loam soils. 

Looking at the geology of the region, most of the Rockpile AVA falls within one specific geological unit. 

Geological map of the Rockpile AVA. Map obtained from the NGMDB

The Rockpile AVA runs along the southwestern shores of Lake Sonoma towards the north. This region is all encompassed by the KJfs formation on the geological map above. The KJfs is the Jurassic to Cretaceous age Franciscan Complex, specifically the greywacke and mélange deposits. The Franciscan Complex is a series of rocks that are termed accretionary (or accreted) terrain. These accreted terrains were added onto North America due to the subduction zone that used to lie on the western shore of California.

Diagram of the subduction zone that was formerly off the western California coast. Image courtesy of the NPS

Starting around 100 million years ago, the Farallon Plate started subducting beneath the North American Plate. As that happened, the islands and other land masses that were on the Farallon plate were scraped off and stuck onto the North American plate in a region known as the accretionary wedge. The Franciscan Complex is such an accretionary wedge that was built up from oceanic crust and pelagic deposits over the course of the Jurassic and Cretaceous. Over time the subduction zone was subducted as well beneath North America, with the remaining parts of the subduction zone only occurring currently along the western coast of Washington, Oregon, and the very northern part of California. 
Extent of the Franciscan Complex in California. Image courtesy of Raymond, 2019.

The rocks within this complex are a large mishmash of materials all thrown together due to the way they accumulated on the continent. As mentioned above, the primary rocks within the Rockpile region are denoted as greywacke and mélange. Greywacke is kind of a bucket term, which is sometimes used for a poorly sorted, grey sandstone. However the Dictionary of Geological Terms 3rd Ed. identifies greywacke (AKA graywacke) as:
"An old term, now generally applied to a dark gray firmly indurated coarse-grained sandstone that consists of poorly sorted angular to subangular grains of quartz and feldspar, with a variety of dark rock and mineral fragments, embedded in a compact clayey matrix having the general composition of slate and containing an abundance of very fine-grained illite, sericite, and chloritic minerals. Graywacke commonly exhibits graded bedding and is believed to have been deposited by submarine turbidity currents.  
The submarine deposition of these rocks makes sense, since they were likely formed along the sea floor before they were scraped off by North America. A turbidity current is an underwater landslide.

On the other hand, the term mélange just typically means a mixture rock blocks of varied sizes and lithologies, not in contact with each other, and surrounded by a finer-grained matrix. Typically these are formed by the process of amalgamation within the accretionary wedge. 
Text from the back of the bottle:
"In 1868 our family established a homestead in the Rockpile area of Northern Sonoma County. The first vines were planted in 1884, starting a tradition of farming that has spanned six generations. Today we craft small production, single vineyard wines that showcase the diversity of Rockpile's rugged terrain. From our vineyards to your glass we thank toy for sharing this tradition" - The Mauritson Family


According to the USGS:

"The sedimentary model suggests that blocks (olistoliths) were transported into the depositional environment of the matrix material by gravity driven debris slides.  The trench associated with the subduction zone provides an area of suitably steep slope for this theory and the converging plates bring the displaced terranes into proximity of the continental margin mélange matrix.  The resulting olistostrome then underwent the deformation described above, disrupting the original depositional character of the matrix/block relationships.  The tectonic model suggests that primary incorporation of blocks into mélange was by tectonic processes.  During and after accretion, lenses of rock derived from incoming exotic terranes were interleaved with continental margin deposits by faulting.  Subsequent deformation during uplift further broke up the lenses of exotic rocks, forming the mélange blocks observed today."

So in summary, the rocks within the Rockpile AVA were formed from submarine landslides that eventually got scraped off the sea floor and jumbled together within the western edge of the North American continent.