Monday, December 21, 2020

Geological Destination - Red Cliffs Recreation Area Utah


One the great things about Utah is that even when not going to the National Parks, there's literally countless little geological oases that one can find themselves in. One of my favorites is a little campsite/park called the Red Cliffs Recreation Area just outside of St. George, Utah. The park straddles the line between two geological formations, the Kayenta Formation and the Navajo Sandstone, with the boundary between the two running right through the middle of the campground.

Starting within the campground, the Silver Reef Trail almost immediately takes you to one of the paleontological highpoints of the area, the Dinosaur Track Site! These dinosaur tracks are located in the uppermost reaches of the Kayenta Formation. The Kayenta Formation is an Early Jurassic (~190 million years old) mix of reddish-brown sandstones, siltstones, and conglomerates that interbed with each other. These were deposited within a meandering river environment and one of the notable features within the deposits are … dinosaur tracks. 

The lighting on these at the time wasn't fantastic but you can still make them out. I also tried to adjust the contrast and lighting on the picture to emphasize them. Dinosaur tracks are a type of trace fossil. Trace fossils, which I go over HERE, are evidences of behavior of animals without the actual animals being preserved; things like worm burrows or fossilized poop or footprints. Trace fossils are also named like regular fossils but instead of being a genus and species, they are named with an ichnogenus and an ichnospecies (ichno meaning trace). The dinosaur tracks found within this park are identified as Grallator and Eubrontes. It should be noted that the makers of any trace fossils is often up to conjecture. Very rarely do scientists find the animal associated with the trace but often it can be narrowed down by the size and build of the animals around at the time compared to the trace morphology. 

A great place to learn about dinosaur tracks is the nearby St. George Dinosaur Discovery site, which has tons of footprints with many of them preserved in place (in situ) and the building is literally built right on top of them. Of the tracks found at Red Cliffs, Grallator is a 4- to 8-inch-long, three-toed print, that probably belonged to a slender, meat-eating dinosaur such as the 10-foot-long Megapnosaurus. Eubrontes (seen in the center of the picture above) is a larger 13- to 18-inch-long, three-toed print, which is thought to be made by a large meat-eating dinosaur such as the crested Dilophosaurus (think the original Jurassic Park but much, much bigger). 

Above the Kayenta Formation is the Navajo Sandstone creating a amphitheater around the campground. Here is a view over the campgrounds with the Navajo Sandstone in the background. The Kayenta Formation is forming the rocks on the very edge of the left side of the image.

The Navajo Sandstone is a rather famous sandstone, being found in many of the national parks in southern Utah creating fantastic geological outcrops, such as those seen here. The Navajo Sandstone is a very thick (~1000 feet) eolian sandstone from an ancient sand sea known as an erg that formed during the Early Jurassic (just slightly younger then the Kayenta Formation at ~180 million years old). This sand sea was larger than the present day Sahara Desert. 

The Navajo is very well known because of the desert features that are so well preserved in it. The most notable is the cross bedding, which is seen in the pictures above and below. Cross-bedding is a depositional feature of sand that forms during the creation of sand dunes. When wind blows sand, the sand bounces along the ground rolling up the side of a dune (the windward side of the dune). Eventually, it reaches the crest of the dune, and falls over the crest of the dune (the slipface or leeward side of the dune). On the slipface, the grains of sand all form into little parallel rows that curve down at the base. These curved lines are what we see when we are looking at cross beds. 

A cross-bedding diagram. Image courtesy of Teach the Earth.

The different sets of curved lines represent different generations of sand dunes that passed through this area. As winds change, frequently with different seasons, the sand dune migrate in different directions along with the wind. These changing sand dune migrations cause the erosion of previous sand dunes, however the bases of some of the sand dunes may be left behind, which is what is then preserved into rock. Then future sand dunes travel over the old dunes, creating new cross beds. 

These sand grains are cemented with other minerals, often calcite or silica (quartz), creating the rock known as sandstone. Because of the nature of these rocks, the cement will often not fill all, or even most, or the pore spaces, creating a very porous rock. This is one of the reasons that sandstone is a popular water or oil/gas repository known as an aquifer. 

The Navajo Sandstone is also known for these pockmark features along it's surface. This is a type of weathering known as honeycomb weathering. Honeycomb weather is produced as water wicks into the porous rock and dissolves the calcite cement holding the grains together. Eventually the dissolution of the cement allows for the grains to be washed away with future rain events. 

One of the cool features of southern Utah is the ability to hike these gorgeous rock units that have remained mostly intact due to the low amounts of precipitation that the area gets. This low amount of precipitation also produces such gorgeous features such as these slot canyons which are a small hike towards the north of the campgrounds called the Red Cliffs hiking trail. The hike continues up the canyon, however it gets a bit harder from here as evidenced by the hand and footholds carved into the rock on the right and the rope used to get up to the top of this little waterfall.

But as the hike continues it is a gorgeous way to soak in the geology. And generally I have noticed that the crowds are fairly small, especially due to the small size of the campgrounds. Sandstone has a tendency to fracture along naturally occurring joints in the rocks. The joints are then further widened by streams flowing through the area creating the slot canyons as they are seen today.

A little bit of a ways to the south of the Red Cliffs Recreation Area is the Quail Creek Reservoir, which is a great place to spend the afternoon. They allow boating and swimming, but what I want to focus on is this great anticline across the water. We are looking towards the northeast but the anticline cuts right through the middle of the reservoir basically towards where I am standing. These are Triassic age rocks of the Moenkopi Formation and the Chinle Formation, which are older than the rocks found just to the north in Red Cliff Recreation Area and would be located below those rocks. 

Wednesday, December 16, 2020

Geological Destination - The Tallest Mountains in the World

 One of the definite geological destinations in my "Must Do" list was visiting the "Tallest Mountain in the World". Now, that's not Mount Everest, which is the highest point above sea level. When measuring the tallest mountain in the world, you need to measure it from the base of the mountain. So here are some of the "tallest" stats:

Highest point above sea level: Mount Everest (at 29,029 feet [8,848 meters]).

Point furthest from the center of the Earth: Mount Chimborazo (at 20,564 feet [6,268 meters]). The Earth is not a perfectly round sphere. The equator bulges a bit so the Earth is a bit larger around the middle than if you measured it around the poles. For that reason Mount Chimborazo in Ecuador ends up being 6,800 feet further from the center of the Earth than Mount Everest.

Tallest Mountain on Earth: Mauna Kea (at 13,803 feet [4,207 meters]). Now, since the bases of both Mount Everest and Mount Chimborazo are on crustal rocks, it causes the heights of both of those mountains to be approximately their elevation above sea level. However, since Mauna Kea is based on the ocean floor, it ends up being a much, MUCH, taller mountain, with the entire height of the mountain measuring at more than 33,500 feet [10,210 meters]. 

Mauna Kea as viewed from the Saddle Road.

Biggest Mountain on Earth: Mauna Loa (elevation at 13,448 feet [4,100 meters]). Second to Mauna Kea as the tallest mountain in the world, Mauna Loa is the most massive mountain on Earth. Overall, it takes up 9,700 cubic miles of mountain. This is much more than Mount Everest or any other crustal mountains since those are often mixed together as parts of mountain ranges, where Mauna Loa is essentially one massive mountain, with the other four volcanos merging together to form the Big Island of Hawaii. .

Mauna Loa as viewed from the Saddle Road

Viewing the two tallest mountains on Earth: As you can see by the pictures above, there is a road, Saddle Road, that traverses the center of the Big Island where you go across the saddle between the two tallest mountains in the world and can get a photo of both of them from a pretty good vantage point. You can also drive most of the way up Mauna Kea and hike the rest of the way, however I wasn't able to do that on this trip. Perhaps next time. And, as a side note, you can see here that even in late March, there is snow on Hawaii. 

Tuesday, December 15, 2020

Geological Destinations - Hawaii's Lava Flows

 Anyone who has been to the Big Island of Hawaii can attest to this as well, but the shear number of lava flows all over the island is simply breathtaking. As a geologist I may have pulled the car over an exorbitant number of times to get random photos of lava flows everywhere we went. 

Lava flow at location A on the map below.

And with all of the lava flows dating from today to back thousands, tens of thousands, and millions of years, Hawaii offers a spectacular opportunity to see how basalt and lava flows age over time. Although Hawaii is a tropical paradise, in places, it also has a wide variety of environments, especially on the Big Island. Due to the rain shadow effect, the eastern portion of the Big Island has a tendency to see a lot more rain with the western portion of the island being more akin to a desert. Therefore the breakdown of the lava flows on the western portion of the island takes a lot longer and we can see the individual stages of breakdown much clearer. 

The lava flow pictured above is located on the northwestern part of the island along the coast where the Mauna Loa lava flows sneak through Mauna Kea and Hualalai.  

Look closer at the geological map of the area (below) we can see the above lava flow at Location A. Here we have two generations of Kau Basalts. The Kau Basalts are the geological name of the lava flows from Mauna Loa. The "fresh" looking lava flows are dated to 1859 CE (AKA AD 1859), meaning these really are fresh. And you can see the fantastic contact with the older lava flows beneath it, dated from 11,000 to 30,000 years ago. Even though the older lava flows date to the Ice Age, you can see that they have really only have sparse vegetation growing within them. 
Geological Map of the lava flow area.

Lava flow at location B on the map above.

Here is another view of the 1859 lava flow. Here the lava flow is basaltic and consists of 'a'a lava, which is a blocky, sharp edged type of volcanic eruption. Mostly all of the lava on Hawaii is basaltic, meaning that it has a low silica content (quartz), is dark in color, has a high iron and manganese content, and has a low viscosity, meaning it flows really well. So many of the lava flows on the island are rather thin, which gives you an impression of how many lava flows it takes to makes an island this big. When you have basaltic lava flows constantly piling up on top of each other you create a type of volcano known as a shield volcano, named for the slight curve to the peak, similar to a shield. 

The older lava flow is a type of lava flow known as pahoehow. Pahoehoe lava has a smoother, ropier texture than the 'a'a. The two types of lava flows (pahoehoe and 'a'a) do not differ chemically at all, they are formed during variations in the eruption process. But these two lava's do weather remarkably differently. The older pahoehoe lava seems to still be intact in many places near the contact with the fresher 1859 lava flow. 

Comparing the much older Kua Basalt to the nearby Hualalai Volcanics at site B, just to the south, gives us a clear view as to how much that difference in eruption can impact it in the long term. Pictured above is the 5,000 to 10,000 year old 'a'a Hualalai Volcanics from the Hualalai Volcano. These lava flows are aged in between the two lava flows above and have started to "rust". This is because of the high iron content within basaltic lava flows that over time the can turn red if exposed to the elements for a long time. This breakdown also allows for the soil to begin to develop. This breakdown process seems to have completely destroyed the original lava flow texture here, while the much older pahoehoe lava are still relatively intact, although with plants growing through cracks in the surface. 

Here we can see the reddish Hualalai Volcanics with the southern extent of the Kua Basalt 1859 CE overlapping on top of it. This location is where the Mauna Loa lava flows are wrapping around the backside of the much smaller Hualalai Volcano before hitting the coast. 
Geologic Map of the Big Island. Image courtesy of the USGS

As you can see above, the island is a mishmash of lava flows stemming from five different volcanos that have been ongoing for thousands and millions of years. And it's super awesome to get to experience that in person. 

And I'll leave this post with one last lava flow. This one is along the southeastern shore of the island, nearby to Punalu'u Black Sand Beach. Here we are looking at a 3,000 to 5,000 years old Kua Basalt from Mauna Loa sticking out into the Pacific Ocean. 

Monday, December 14, 2020

Geological Destination - Hawaii's Punalu'u Black Sands Beach

Beach Sands

Beaches come in all shapes and sizes, however the vast majority of beach sands are made up of quartz. These are the beaches where the sand is the color of, well, sand. It is that light orangish hue that sometimes grades towards white. It is a hue so common in the world that the name "desert sand" was even adopted as an official palette color. 

Desert Sand Crayon. Image courtesy of Ranker.

This "typical" sand is made up of quartz grains that had been eroded down into "sand-sized" grains, coated frequently in a microscopically thin layer of iron-oxide, giving it its unique hue. The reason why sand is frequently comprised of quartz is that quartz is one of the most abundant minerals on the surface of the earth, making up a large majority of the rocks on the surface such as granite and sandstones. It is also extremely hard compared to other minerals (a 7 out of 10 on Moh's hardness scale), it has a fairly simple crystal structure comprised of only two elements (SiO2), and it doesn't have cleavage, the ability to break along plains of weakness in the mineral. This means that as it erodes, it erodes down into a small ball, instead of breaking down along flat edged blocks. 

With granite being one of the most abundant rock in mountains, and beaches composed of sand from the breakdown of mountain rocks, then that being the case, it is rather rare to have a beach NOT comprised of quartz sand. Beaches get their sand from rivers that carry eroded sediment from local or distant mountain ranges. Over the course of the river, the rocks from the mountains are broken down into smaller and smaller pieces, until all that is left is the most resistant mineral grains. 

However, sometimes you can get beaches comprised of different minerals or chunks of rock than quartz. There are a few ways this can happen. One way is that these minerals and rock chunks can come from sources closer and more local to the beach, so that they haven't had the distance and time to erode down all the way. Or you can have an instance where quartz is not present in the source rock at all, or much less abundant than other minerals. Both of these occurrences are what we have in Hawaii. 

The Geological Context of Hawaii

Diagram of the creation of the Hawaiian Islands. Image courtesy of Clark Science

Hawaii is a volcanic island made up from the volcanic eruptions of a hotspot deep within the mantle. A hotspot is a non-moving plume within the mantle that melts the crust on top of it. However, the Earth's crust moves around on top of these hotspots. As the Pacific plate moves over the Hawaiian hotspot, it melts the crust and creates a series of volcanoes as it passes over. That is the string of Hawaiian Island, where the only active volcanoes are located on the Big Island, where the hotspot is currently located.

Hawaii's volcanic rocks are composed of Basalt. This is a silica-poor rock, meaning that it lacks any quartz in it whatsoever. Basalt is also very black in color. And being located nearly in the center of the Pacific Ocean, away from any other sources of rocks, all of the sand on Hawaii needs to come from the islands themselves. So since Hawaii doesn't have quartz, what is the sand comprised of? Well, that depends heavily on which island you are on and where you are located on that island.

Hawaiian Beach Sands

This is a shot of Magic Sands Beach Park on the western shore of the Big Island. Looks like quartz sand, doesn't it? But I just said there was no quartz in the volcanic eruptions, and the basalt, which is the primary rock type, is black. But this isn't black. Let's take a closer look.

When you look real close at the sand, not only are there chunks of black, like predicted, but all of that white and tan colored stuff isn't quartz. Quartz beach sand typically has a polished glass look to it when you look at it real close, however here, this sand looks opaque and generally has an angular appearance to it. This is because the sand is made up of animal shells and broken up pieces of coral reefs, which are both composed of calcite. So the majority of this beach is calcite sand, not quartz. And calcite is a much softer mineral than quartz (which has a Mohs Hardness of 3, about as hard as copper), allowing it to break down much faster than quartz but also be softer on to feet than quartz sand. These grains of coral sand are generally produced as poop from the parrotfish, which ingests the calcite while eating algae off of the corals and other rocks but can't digest it. 

Black Sands Beach

So that's the white sand beaches, but since Hawaii in composed mostly of black rocks, shouldn't there be "black sand" beaches. And indeed there are. One of the most famous is Punalu'u Black Sands Beach on the southeastern shore. 
Location of Punalu'u Black Sands Beach

At Punalu'u Black Sands Beach, the sands really are black. You can even see many of the lava flows that formed this part of the island still on place along the shores that aren't covered in sand. 

Here the sand is made up of tiny eroded pieces of basalt that when looked at closely really resemble that chocolate rock candy a lot. 

Map of the Big Island volcanoes. Image courtesy of the USGS.

When looking at the location of Punalu'u, it sits almost exactly at the junction of the Kilauea and Mauna Loa volcanic eruptions as see on the map above. 

Taking a zoomed in look at the area. The arrow is pointing to Punalu'u Beach. Here we can see that the Kau Basalts surround the beach area. Kau Basalts are the ones erupted by Mauna Loa. The lava flows on the beach, inland of the beach, and to the southwest of the beach are all lava flows dated from 3,000 to 5,000 years old. Directly across the inlet on the northeastern shore of the inlet contains much younger lava flows from Mauna Loa dating from 1,500 to 3,000 years old. 

Here is a view of the beach from a little higher in elevation and back from the shore a bit. These lava flows are the 3 to 5K Kau Basalt lava flows. Looking out across the water, where a lot of the greenery is located, are the 1.5 to 3K Kua Basalt Lava flows.

But since the sand on a beach doesn't just come from the sand in the local environment, there is likely to be other basalt sources in this sand, and that's where the Kilauea Volcano comes in. It is actually very close to this beach, just around the point across the water. On the the geologic map, all Kilauea volcanic eruptions are identified as Puna Basalts. With the large land mass around the point dating from 400 to 750 years old. And there is an even older, covered over lava flow directly uphill, and upstream, from hear on the geologic map dated from 5,000 to 11,000 years old. 

Both of these volcanoes contributed greatly to these black sands beaches. And you even have the small assortment of coral and shell pieces mixed in, just as at the Magic Sands beach above, but to a much smaller percent. 

The differences in the beaches can be attributed to the directions of the winds, and therefore the ocean currents around the islands. The wind patterns generally blow from east to west across the island. This is what creates very rainy weather in Hilo (on the eastern shore), while you get dryer weather in Kona (on the western shore). These winds and ocean currents then create a haven for coral reefs along the western shore, while the southern shore is much more limited of coral life.

Due to the short transportation distance from mountain (volcano) to beach, the sand grains don't have the ability to be sorted out by size as much as much more mature landscapes do. This is the reason North American east coast beaches tend to have beaches completely composed of the same sized sand grains. Water is a marvelous sifter, both river water and ocean/wave currents. But here, the rivers and streams are much shorter to the beach, so you have a much wider variety of rock and sand sizes founds. Where large cobble sized rocks are mixed in with the smaller sand size grains.  

But regardless of the geological context, the Black Sands beach is a marvel to behold and well worth the trip to see it. Nearby here, there is also the Green Sands beach, which has a high concentration of a basaltic mineral known as olivine. However, I wasn't able to visit that beach on this trip. Perhaps next time. 

Saturday, December 12, 2020

Dinos in Pop Culture - Gummi Dinosaurs

 I'm a sucker for dinosaur related foods and I found these. Although the odds of them all getting gummied and winding up together are fairly small due to the wide time difference between the T. rex, Stegosaurus, and Apatosaurus(?) I think it is still a fun paleontologically related snack. 

Check out my other food related geology posts HERE

Thursday, December 03, 2020

Geology Through Literature - The Tin Drum

 Geology Through Literature: The Tin Drum

Despite the main character of The Tin Drum by Günter Grass working for a headstone carver, there isn't much geology in the book. There are frequent off-handed mentions of different rocks such as granite or marble, but nothing that could be placed in context. There is one instance in the book, though, that we could delve into.

Book 2, Chapter "He Lies in Saspe"
"The (Saspe) cemetery was square with a wall running around it. We went in on the south side, through a little gate that was covered with ornamental rust and only supposed to be locked. Most of the tombstones were of black Swedish granite or diorite, rough hewn on the back and sides and polished in front."
The Saspe Cemetery is on the outskirts of Danzig, Poland, which is now known as Gdańsk. Gdańsk is a port city located on the Baltic sea in northern Poland. This means it was directly across the water from Sweden and could easily have received Swedish stones. 

Although many non-geological people will call anything that isn't marble "granite", I don't think that was the case here. Specifically, because he calls out diorite as an alternative to the black granite. Looking at the igneous rock scale (a generalized version) we can see that igneous rocks are identified by the minerals located within them.

Diagram of igneous rocks as identified by their present minerals. Image courtesy of

For the rocks in the three leftmost columns, there are two rocks each. These identify the course grained rocks (granite, diorite, and gabbro), that formed as intrusive igneous rocks. This means that they formed from a body of magma (molten rock) that cooled over a very long time underground. This allowed the crystals to grow to a point where individual crystals are easily identifiable by the naked eye. The second set of rocks are for the fine grained rocks (rhyolite, andesite, basalt). These rocks are extrusive igneous rocks, also known as volcanic. These rocks formed from lava (magma that had been erupted), and cooled very quickly. The quick cooling caused the mineral grains to be very small and mostly unobservable to the naked eye.

When you look at the rock groupings from left to right there are certain patterns. One is that the amount of silica (quartz) decreases. There is also less Orthoclase Feldspar are you move to the right. These are both generally light colored minerals. The minerals more on the right (plagioclase, pyroxene, micas, and amphibole), these are generally more darker colored minerals. So as you move from left to right, the rocks get darker in color. 

A "black granite", aka Swedish diabase from Scandinavian Stone's Gylsboda Quarry. Image courtesy of Scandinavian Stone

The use of the term "black granite" already had me questioning if this was a real thing. However, after doing some research it appears the term "black granite" is applied to rocks that "share the hardness and strength" of granitic rocks, despite them not actually being a granite. Generally, these "black granites" are what are known as a diabase (also known as dolerite), which is a microcrystalline gabbro with crystal sizes (and therefore cooling rates) falling in between gabbro and basalt.  

Globally, Sweden isn't generally known for their building stones. However, that doesn't mean that Sweden should be ignored. They actually have a significant amount of building stones that they frequently will quarry and send off to other countries, such as Italy, Spain, China, or Poland for processing. The size of the industry in Sweden is very small though, totaling ~1,200 people with three separate companies comprising the bulk of that number. 

Diabase from the Swedish Gylsboda Quarry. Image courtesy of Scandinavian Stone.

Within Sweden, there three main rocks that are quarried, among them several varieties of "black granite" AKA diabase. This includes the rock types known in the construction industry as Black Bonnacord, Black Finegrained variety, Black Ebony, Black Gylsboda, and Grey Bohus. The problem with these industry names though is that they more reference the color and texture of the rock and not any particular geological occurrence. I actually found one quarry (Black Diabase Brannhult Quarry) That has several of these types of rocks all listed within the same quarry, further emphasizing that these are likely variations on the same rock formation.

Diabase from the Swedish Hjortsjö Quarry. Image courtesy of Scandinavian Stone.

But the one thing I did find, is that many of the diabase quarries were in the south central part of Sweden, in the region called Småland (which is not only the name of the Ikea day care apparently). Looking at the geologic map below the southern portion of Sweden can be broken down into two distinct provinces, the eastern province known as the Transcandinavian Igneous Belt and the western province known simple as the Eastern Segment. 

Southern Sweden geology. Image courtesy of Salin et al., 2019.

The problem is that many of the quarry locations are falling very close to that central area between the two provinces known as the Protogine Zone, which is a major faulted shear zone. However, upon closer inspection, it appears that these quarries, which all are within a generally small region, are a part of the Transcandinavian Igneous Belt within an area known as the Småland-Värmland granitoids.

More detailed southern Sweden geologic map. Image courtesy of Högdahl et al., 2004.  

The above geological map indicates that these diabase deposits are dated to around 1.85 to 1.65 billion years old. However, diabase, is often deposited as smaller igneous bodies within a larger body, such as a sill, dike, lopolith, or a laccolith. The smaller igneous body allows for some slow cooling, but not slow enough to form a full on gabbro. Therefore the dates on these larger bodies is likely too old and the actual diabase would be younger than that. However, I don't think they would be too much younger since the magmas that formed the larger Transcandinavian Igneous Belt are likely related to the diabase producing magmas.

On the map above it also lists some other provinces of dolerite (the other name for diabase) towards the northern end of this region. The quarries that I researched are not harvesting this diabase, but that doesn't mean that another company isn't. This diabase is dated to 1.25 billion years old and I would image the diabase in the southern portion of the country would date around the same.

So in general, the "Swedish black granite" mentioned in the text was likely obtained from these southern diabase deposits within the Småland-Värmland granitoids. It also works out that since these are along the southern coast of Sweden, the transportation distance to Poland would have been much less across the Baltic Sea to the east.