Thursday, February 25, 2021

Geological Destination - Ship Rock

Nearby to Four Corners Monument, and actually used during the original survey of the monument, is the monumental geological feature of Ship Rock. It is located in northwestern New Mexico, near the town of Ship Rock on the Navajo Nation. It is also known as Tsé Bit'a'í, or "the winged rock" in the native Navajo language.

View of Ship Rock from the south

Ship Rock is the volcanic remnant, or volcanic neck, of a prehistoric volcano that erupted ~30 million years ago. Ship Rock intruded within the much older Mancos Shale, a Cretaceous age (~90 million years old) formation made up of mostly claystone and siltstone with minimal amounts of sandstone and limestone that formed on the bottom of the Interior Cretaceous Seaway that once dominated the central portion of North America.

Geological map of Ship Rock, NM. Image courtesy of the NGMDB.

Part of the Navajo Volcanic Field, Ship Rock formed as what is known as a diatreme, a volcanic vent or pipe that was forced through flat-lying sedimentary rocks producing an expanded vent through explosive energy. The main portion of Ship Rock is composed of volcanic breccia, made up of a type of potassium-rich volcanic rock called "minette", which is thought to be formed from melting of the mantle. Ship Rock itself is ~1,600 feet wide at its widest and ~1,600 feet tall. When the volcano intruded into the Mancos Shale, it is thought that the current visible features were solidified ~2,500 to 3,300 feet below the surface of the Earth. However, the extreme weakness of the Mancos Shale has allowed extensive erosion to occur, carrying away the shale while leaving behind the much harder volcanic rock. 

View of Ship Rock from the south and the southern dike.

One of the more notable features of Ship Rock are the radiating features that emanate from the pinnacle itself. These were formed as volcanic features known as dikes. Dikes are vertical intrusions of magma into a surrounding bedrock. The vertical intrusion then hardens, leaving behind sheets of lava rock. Radiating outward from Ship Rock are six different dikes. These dikes can be seen on the geologic map above as red lines. However, due to the size of the southern dike and the distance to Ship Rock, I was only able to get a picture of the main southern dike.

View of the southern Ship Rock dike facing towards the south, away from Ship Rock.

View of the southern dike, facing towards the north, at Ship Rock

Closer up view of the southern dike.

It should be noted that Ship Rock is considered sacred to the Navajo, and while viewing the rock is allowed, climbing and hiking on the rock are prohibited.

A bit more of a distant view of Ship Rock. The two points on the right side of the photo are remnants of two of the smaller dikes that radiate out towards the northeast from Ship Rock.

On a recent trip to Canyon de Chelly National Monument, in the gift shop there was some additional information about Ship Rock and its Native origin story.

The story reads:
"Shiprock" 
(Naayee, Tse'bi taahi') 
Shiprock was once a Monster in our Navajo culture. Rock with wings (Naayee, tse'bi taahi') it was one of the most feared monsters of 10 different monsters in our Navajo Lure. If you look at it, a big piece of rock over 1000 feet was how tall the monster was. The Monster Shiprock would pick up people and drop them below into the jagged rocks and eat them. The Dine People feared him and the people wondered how these Monsters came to be. 
As the story goes, during this terrible time, the people (men and women) separated from each other causing conflict over who was going to be the leader. From there, they all went their separate ways. The men had problems without the help from the women and the women became promiscuous which resulted in deformed babies. They were ashamed of it, so they hid their babies. The deformed babies became Monsters. 
Changing Woman came to the rescue of the Dine. She too had babies (twins), one born for water and the other born for the sun. The twins asked their mother who their father was, finally she told them. And they began their plan to visit their father Sun, who helped them by forming them into humans. 
The Sun tested them to see if they were his real kids. Luckily, they passed all the tests given. As the end approached, their father asked why they came. The twins told him that there are many Monsters killing the Dine and they had come for weapons to kill the Monsters. 
The father Sun was worried and gave each twin a weapon and they came back down on a rainbow. The twins killed all the Monsters including the one Monster which is known today as Shiprock.


Drawing of the Monster which became Shiprock.


Wednesday, February 24, 2021

Geological Destination - Four Corners Monument

Being located at the junction of four states, Four Corners Monument might just as well be considered a political park. However, geology is everywhere and therefore this is a perfect example of a geological park as well. The Four Corners Monument is a Navajo Tribal Park that designates the boundaries between the states of Utah, Arizona, Colorado, and New Mexico. It also designates the boundaries between the Navajo Nation and the Ute Mountain Ute Tribe Reservation. We visited the park on my birthday back in March of 2019. 

Me, laying across all four states at the monument. 

It has been said, by many people, that this point does not actually represent the point of intersection of the four states. These people are wrong. As noted by NOAA:
"... the Four Corners monument was established at the point he [surveyor Chandler Robbins] determined, to the very best of his ability and using the available technology, to be the prescribed location of 109 degrees 03 minutes West longitude and 37 degrees North latitude."
This precise location, however may be off by ~1,800 feet to the west of the monument. However, since this point was surveyed as the junction of the four states, and approved by the governments of the four states as well as the federal government, it IS the location of the junction, regardless of what the original intention of the surveyor may, or may not, have been.

It should also be noted that acclaimed geological landmark, nearby Ship Rock, was used as one of the marker locations for the designation of the Four Corners Monument. My next post will be on Ship Rock.

A closer look at the geodetic survey marker, designating the actual Four Corners point.

The Four Corners Monument sits within the Colorado Plateau. An area that is being forced upwards by the subducted Farallon Plate. 
Location of the Colorado Plateau. Image courtesy of Woodward, 1973.

Starting ~100 million years ago, along the west coast of North America was a subduction zone. This is where one plate goes beneath another plate. In this instance the Farallon Plate subducted, or went beneath, the North American Plate.

Graphic of the Farallon Subduction. Image courtesy of the NPS.

Over time the majority of the Farallon Plate was completely subducted, including the mid-ocean ridge (aka spreading center), leaving behind a new type of plate boundary along the coast of California. Instead of a subduction zone, there now was left a transform plate boundary, where one plate slides passed another one. This plate boundary is better known as the San Andreas Fault. Remnants of the Farallon Subduction Zone still exist along the coasts of northern California, Oregon, and Washington. 

Over the past ~10 million years, the subducted Farallon Plate was still a very hot plate, and therefore wanted to rise up underneath the North American Plate. Because of this, the Farallon Plate started to push upwards on North America, creating a region of the continent that is rising vertically upwards compared to the surrounding regions. This is the Colorado Plateau.

The geological features of the Colorado Plateau surrounding the Four Corners Monument. Image courtesy of Woodward, 1973.

The Colorado Plateau is made up of many of the world's most beautiful landscapes because of these geological forces playing around in the region. Looking specifically at the Four Corners region, anyone who has been to the Four Corners Monument will also notice that this area is a relatively flat, mountainless plain. This region is known as the Four Corners Platform. The platform is a relatively flat region that sits as an intermediary between adjacent basins and uplifts. In an area surrounded by mountains and canyons (and several anticlines (A-shaped bends in the rocks)) this region just happens to be in the middle of it all forming a flat surface. 

Geological Map of the Four Corners Monument. Image courtesy of NGMDB.

Looking at the rock units that cover the Four Corners Monument, they are represented on the map above by the symbols Jmw and Jmb, These are both members of the Upper Jurassic Age (~585 million years old) Morrison Formation. The Brushy Basin Member (Jmb), which covers the actual monument, is an interbedded green, purple, and grey mudstone and siltstone with grey and tan sandstone and conglomeratic sandstones. Known for its dinosaur fossils, the Brushy Basin Member was deposited from prehistoric rivers (fluvial) and lakes (lacustrine). The underlying Westwater Canyon Member (Jmw), is a yellowish-grey sandstone containing conglomeratic lenses and dark-reddish-brown siltstone. The Westwater Canyon Member is also a fluvial (river) deposited unit.

References

Tuesday, February 23, 2021

Geological Destination - Dead Horse Point State Park

 Just outside of Moab, UT, lies a State Park with fantastic overlooks and great geology. We stopped at Dead Horse Point State Park on our way to Canyonlands National Park back in March of 2019. The two parks are pretty close to each other and we had heard good things about the state park. And we were not disappointed.

The name of Dead Horse Point comes from a legend where cowboys would fence off wild mustang horses along the overlook, taking what horses they wanted and leaving the horses they didn't penned up to die of thirst. But despite the grizzly imagery, this is a beautiful location.

Looking off towards the southeast from the overlook is the Colorado River far below. Between us and the river lies 100 million years of geological history. From top (youngest) to bottom (oldest) the rock units go like this:

Entrada Formation: Jurassic (150 million years old) - This is a sandstone formed from a coastal dune environment. These are what the arches at Arches National Park are found in.

Navajo Sandstone: Jurassic (175 million years old) - Wind deposited, prehistoric "petrified" sand dunes from an ancient erg (sand sea), colored a light tan or white color. The units also preserve phenomenal cross bedding features from the sand dunes. These rocks form the majority of the rock formations in Zion National Park.

Kayenta Formation: Late Triassic (180 million years old) - A series of sandstones, shales, and limestones from a meandering river environment that frequently preserves dinosaur tracks. This formation is very well observed in the nearby Canyonlands National Park.

Wingate Sandstone: Triassic (200 million years old) - Like the Navajo, another wind deposited preserved series of sand dunes, however usually with more of a red tint to the rocks (rust). 

Chinle Formation: Triassic (210 million years old) - A stream deposited series of mudstone, sandstone, and conglomerates. Well known for containing uranium deposits, petrified wood, and fossils. You can see some of the ancient uranium mines in nearby Capitol Reef National Park.

Moenkopi Formation: Early Triassic (230 million years old) - A tidal flat deposited series of brown to red mudstones. The rocks will often feature ripple marks and raindrop imprints. You can see this formation especially well along the western entrance to Capitol Reef National Park.

Cutler Formation: Permian (250 million years old) - Comprised of sandstone and conglomerate, this formation was deposited along a coastal-marine beach with off-shore sands and non-marine alluvial floodplain deposits intermixed. The most notable feature of the Cutler is the White Rim Sandstone.

Honaker Trail Formation: Pennsylvanian to Permian (286-320) - Down at the level of the river lies this shallow sea deposit comprised of dark grey limestones with fossils. 

Off in the distance to the east of the Point are some Solar Evaporation Ponds. These are rather striking in the sea of reds and browns that I'm glad they had an interpretive sign to help understand what you are looking at. 

Description of the salt deposits being mined.

This entire area is part of the Colorado Plateau and is the reason that we have the Colorado River formed within the canyons as you can see here. Over 10 million years ago the Colorado River was flowing along a gently sloped floodplain, being allowed to meander as it needed to. Then the area was forced upwards. This occurred when the Farallon Plate, a large plate that was subducted below North America off the western coast of the the US, began to push upwards on the region. As the region was forced upward, the rivers that were formally allowed to meander naturally, started to erode downwards into the underlying bedrock. This downward erosion locked the rivers in place, creating a feature known as an entrenched meander. Besides just here, you can see this feature all over the Colorado Plateau including at the Grand Canyon National Park, Natural Bridges National Monument, and Goosenecks State Park.

Monday, February 22, 2021

Dinosaurs!: From Cultural to Pop Culture - 1987: Robocop

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1987: Robocop

Located within 1987's Robocop by Paul Verhoeven, is a classic example of dinosaurs within pop culture, especially renditions of dinosaurs that didn't keep up with their scientific equivalents. 

The movie Robocop is broken up by several fake, in-universe movies, including this one for the 6000 SUX, a gas guzzling vehicle that gets 8.2 mpg. The dinosaur "commercial", located at the 1:15:59 minute mark, uses a classic stop-motion dinosaur effect, similar to those seen in 1933's King Kong, as well as many movies afterwards through the 1950's and 1960's. 

Dinosaur from Robocop (1987)

The dinosaur in the commercial is a questionable species, not really resembling anything known to have existed. It is a clearly a theropod, similar to a T. rex, however with three digits on its hands like an Allosaurus with relatively long arms. It is also looking to be about 5 stories tall, or ~75 feet tall, based on the building in the background. This is far taller, even with the antiquated upright stance in the commercial, of any known theropod. At this height, this dinosaur is reaching the height levels of the tallest dinosaurs to ever have lived, like the Sauroposeidon proteles. 

Up front close up of Robocop's (1987) dinosaur.

The commercial dinosaur also has a series of horns/spikes above its eyes, like Carnotaurus. However, Carnotaurus only had one spike over each eye, and also had significantly reduced forelimbs, similar to T. rex. 

Carnotaurus reconstruction from Dinosaur Wiki.
   

Friday, February 19, 2021

Dinos in Pop Culture - Star Trek: Voyager - Entry 3

 And the last of my Star Trek entries into the Geology and Dinos in Pop Culture is perhaps the greatest dinosaurian related episode of Star Trek to date. The episode is from Star Trek: Voyager, Season 3, Episode 23, entitled "Distant Origin.

This clip above is just a small portion of the episode, in which I highly recommend watching the whole thing if possible. In the episode, the crew of the Voyager are faced with the Voth. A species that, after some genetic determination, evolved from hadrosaursians and somehow ended up across the galaxy into the Delta Quadrant. Their supposition was that this hadrosaurian species survived the extinction of the dinosaurs and were isolated on an island, where eventually they evolved space-faring technology to somehow eventually leave Earth and end up across the cosmos. The best part is when they start researching the history of the Voth, leading them to Eryops, "from the Devonian era". 

Eryops from the Star Trek: Voyager episode "Distant Origin"

Their reconstruction of Eryops though, does not actually resemble the current reconstructions (pictured below). Nor is it from the Devonian, having been found in Permian deposits over 100 million years later. However, this reconstruction looks amazingly like a pelycosaur, like Dimetrodon, just without the sail.

Eryops reconstruction from Britannica

Eryops was an amphibian, and was supposed to stand in as the "last common ancestor of cold-blooded and warm-blooded organisms." My assumption is that they were looking for the split between mammals and reptiles. However, that is not entirely an accurate thing, since mammals evolved much later. What we need to search for is the split between Synapsids (the group that evolved into and includes mammals) and Diapsids (the group that includes crocodilians, dinosaurs, and birds). Both of these groups fall under the classification of amniotes. 

The branch between these groups is thought to have taken place in the Lower Permian, approximately 300 million years ago and would have involved early synapsids, such as the pelycosaurs (kind of pictured in the show). And although pelycosaurs are considered basal synapsids, not the ancestors to both dinosaurs and mammals, it's not out of the realm of possibility that the actual ancestor would have several similar characteristics. 

Dimetrodon skeleton. Image courtesy of ScienceSourceImages.

So although their name dropping of Eryops was 100% incorrect, perhaps their model was a bit closer to reality. 

The show also asks what was the "most highly evolved cold-blooded organism to develop from the Eryops" and the show pictures a Hadrosaur. Specifically, a Parasaurolophus. 

The "most highly evolved" dinosaur according to Star Trek: Voyager.

Evolutionarily speaking, all reptiles, and this includes all dinosaurs/birds, would have evolved from the basal diapsids. So by saying the "most highly evolved", you are making assumptions that one organism is more evolved than another one, which is not how evolution works. There is no organism that is "more highly evolved" than another. Each organism is adapted to their own environment. I am assuming by "more highly evolved" they mean more intelligent, which is another matter entirely. And even then, it is assumed that the theropod branch of dinosaurs, the one that evolves into birds, would be much more intelligent than the sauropods, which were larger and lumbering herbivorous dinosaurs. Heck, the birds even survived the end Cretaceous extinction, which none of the Sauropods did. (well except this one branch that went off into space.

So, however you see it, this episode was a dinosaur wonderland. 

Saturday, February 13, 2021

Geology in Pop Culture - Star Trek: Voyager - Entry 2

 Continuing on with the Star Trek geological entries is Voyager again. 

While doing some geological analysis down in a cave looking for dilithium (a fake mineral in the Star Trek universe), Chakotay, Kim, and Neelix are doing various geological scans of the cave including a "geo-strato analysis". Eventually Neelix is attacked and Tuvok and Janeway travel down to the caves where they discover an excessively warm bit of rock. According to Tuvok "There are no natural geological phenomena that could be creating this heat source," prompting the team to fire their phasers on it.

Thursday, February 11, 2021

Geology of the National Parks in Pictures - Great Basin National Park

 My next post about the Geology of the National Parks Through Pictures is from one of the closest National Parks to our house, yet one that we didn't visit because it was so far out of the way from anything.

You can find more Geology of the National Parks Through Pictures as well as my Geological State Symbols Across America series at my website Dinojim.com.

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Although Great Basin is within a few hours of our house, it did take us living here for 11 years before we ventured out towards it since there is absolutely nothing on the way to the park, and really not much in the way of places to stay once you get there. We had a trailer by this time, that we took with us to camp in the first come-first serve campground and we got a fantastic spot. However, we were later kicked out of the campground because snow melt was washing out the road to the campground. So we ended up just outside of the park, in the literal middle of nowhere. But we got what we went to do, which was tour the park and tour the main attraction, the Lehman Caves. 
Entrance sign shot showing the South Snake Range mountains, which are mostly encompassed within the park.

Within the main part of the park stands Wheeler Peak at over 13,000 feet tall. There is a road that goes most of the way up to the top, however it was closed when we were there (at the end of May) due to snow coverage on the road and was still too high to remove. However, we were able to hike up the road a bit. 

The views up Wheeler Peak Scenic Drive were spectacular, overlooking the surrounding valleys. The mountains and all of the surrounding valleys sit within the "Great Basin" of which park is named after.  

Another view of the valleys from Mather Overlook, which is the highest we could drive up the Wheeler Peak Scenic Drive at just over 9,000 feet in elevation. The Great Basin was formed as part of the Basin and Range Province of the United States. 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 is not able to flow out of the Great Basin, hence the terminology of "basin". Unlike water along the eastern portion of the country and along the west coast, water here does not reach the oceans. All precipitation here eventually ends up in end-basins, such as the Great Salt Lake, where its only outflow is through evaporation.

The rocks within the South Snake Range are mostly comprised of sedimentary rocks like sandstones, shales, and limestones that were all deposited during the Cambrian Period, around 550 million years ago. Seen here is the principle limestone of the region, the Pole Canyon Limestone, and the one in which the Lehman Caves was developed within. The Pole Canyon Limestone was deposited within a warm, shallow sea near the equator. This limestone formed from the dead shells of ancient sea creatures that built up over time. These shells, made up of calcium carbonate, naturally dissolve in acids, even if the water is only slightly acidic.

Over time the limestone was slightly metamorphosed (producing small amounts of marble). It was also  cracked and fractured from the mountain building events (orogenies). You can also see that the limestone was rotated during these events, as seen in the lower part of the cave map. As the rocks cracked, this allowed ground water to seep into the limestone. The groundwater, which becomes carbonic acid by absorbing carbon dioxide from the soil and air, slowly dissolved away the limestone as it passed through the cracks. Over time, those cracks widened from the dissolution. 

Here is the original, natural cave entrance to Lehman Caves. This is up above the current entrance, which was blasted into the caves through the limestone walls. 

As the water dissolves the limestone, it also deposits limestone. This is how cave formations are formed. The tiny bit of calcite that is within the dissolved water precipitate out of the water as the water drips off the surface of the rocks. Here stalactites are continuously formed and getting bigger as water runs down them from the overlying limestones. Calcite deposits on the tip of the stalactite, and whatever calcite remains within the water can then get precipitated directly below the stalactite on the ground as a stalagmite. These eventually will meet to form a column, as seen here in the background. 

Lehman caves is covered in absolutely gorgeous formations throughout the caves. 

Some of the thinner, soda straw, stalactite formations. 

Looking up at some of the stalactites directly above the narrow passage. 

View of some of the fantastic cave formations.

More soda straw formations. You can see here the tube through which the water is traveling, giving the soda straws their name, from the overlying limestone. As the water reaches the end of the straw, calcite is deposited at the tip, creating new straw layers as the stalactite grows. Eventually these straws will close up and build outwards, producing the more typical stalactite formations. 

There is even standing water within the caves here, that very slowly seeps down into the limestone and other rock formations below the cave floor. 

Some more columns, stalactites, and stalagmites. 

More cave formations. Here showing a few of the "draperies", which are cave formations formed as water flows down the the side of the cave. These are more often known as flowstones. 

Some of the more delicate features within the cave. All cave formations form a type of rock known as travertine. Travertine is a product of the flowing water precipitating calcite, and can be formed within caves as seen here, or outside caves where flowing water is precipitating calcite, such as around geothermal features.

References

Friday, February 05, 2021

Dinos in Pop Culture - Star Trek: Enterprise - Entry 3

 And the last of the Star Trek: Enterprise entries is a paleontological mention. 

From Season 4, episode 19 "In a Mirror, Darkly, Part II", the crew is in the Mirror Universe and is being attacked by the infamous Gorn from the Original Series. While they are trying to figure out what did it they comment that they had "traces of reptilian saliva in the ... wounds" and the bite radius indicates a reptile that is more than 2 meters in length. When asked if this was a pet, the response was "Unless one of them owned a velociraptor, I find it extremely unlikely."

Gorn from Star Trek: The Original Series. Image courtesy of Memory-Alpha.

Gorn from Star Trek: Enterprise. Image courtesy of Memory-Alpha.