Month: March 2020

Wet Day with Grapes

In these days of the Corona-virus I don’t get out as much as I like to. But when I have an opportunity to get out, I usually go. Last Sunday I went out to a small National Park which has some good hiking trials. But it was so crowded that I did not even park my car. After visiting three trailheads I turned around and headed home. It’s not very far from where I live, so going out and coming back is not any trouble for me.

It was late afternoon when I went out as that is when I like to hike. When I got to the entrance road, I could see there were cars parked all along the drive. This meant that at some point in the day the main parking lot had been full. And it may have still been full. When I saw all the cars parked along the road, I knew that part of the park was more crowded than I like it. So I drove to another area in the park where there are some excellent trails. Here again the same thing. Cars and trucks parked all along the road up to the small parking area (3 spaces) at the trailhead. When I saw this, I passed it by. The third area was the same. At this area I could see down the paths that cross the mown fields, and I could see large groups that I would likely have to intermix with. That’s was my last chance, so I drove on home.

Although I was disappointed in missing my walk, I didn’t mind because I was taking charge. As Dr. Fauci has told us time and again, we are not in charge of the timetable for transmission of the COVID-19 sickness. This new virus, the novel Corona-virus, is in charge. But we can be in charge of what we do, of how we react to the presence of the virus. As he tells us the best thing we can do right now is do your best to prevent the transmission to ourselves and to others. We must follow the social distancing guidelines. We must avoid public areas as much as we can. We must protect ourselves, and thereby protect the hospital workers who we might pass on the trail or who live in our neighborhood.

But what about the grapes? Was it raining last weekend?

No, it was not raining last weekend. I took this picture of the grapes dripping water last year in late summer. I was in the same park but down by the broad creek that forms the boundary of the park.

The grapes were just beginning to grow, and so were quite small. I doubt that they would have grown to full size fruit as there are many animals and birds that enjoy the grapes, at whatever stage the fruit may be. I don’t eat them since wild grapes can be rather sour if you get them too early. And even if you wait until they are fully developed, they are still rather tart. As the grapes ripen the blue jays and other birds will fly in and sit on the thicker parts of the vine while they eat the grapes When the grapes are a bit riper, the raccoons and possums will climb up and pluck them off the vines.

Up in the woods of the Virginia foothills, I use to walk in a State Park in the Blue Ridge where there was a big grape vine there that the kids could pull themselves up on. I imagine that it was decades old. At my home in North Carolina there was an old grape vine that had been growing and hanging from a tree deep in the woods for as long as I could remember. The tree was toppled by a hurricane several years ago and the grape vine which was about 6 inches across had to be cut so the tree and its branches could be removed. I’m still hoping that the shoots I have seen on that stub will continue to grow for another 50 – 100 years.

These vines of wild grapes are all through the southern woods. They are a welcome sight as I know that the birds and the beasts enjoy them. And seeing the big vines hanging from the trees always make me smile as I think back to the first vine that I ever swung on.

But be careful; don’t grab hold of a poison ivy vine. They are in the same woods. Know what you are grabbing hold of. If the roots of the vine and where it is attached to the tree have “hair” growing out onto the tree the vine is climbing don’t touch it. Its poison ivy.

I hope we are all back in the woods soon. And please remember to always wash your hands.

I believe the grapes pictured are Riverbank Grapes (Vitis riparia).

DINO Tracks

On a recent trip to New Mexico, before we had to hustle back home, we visited an exposed dinosaur trackway in the north-east corner of the state.

For me visiting these sites is an experience in time travel as much as it is in science. The tracks at Clayton Lake State Park were made in the early Cretaceous period about 100 million years ago. At this time in Earth’s geology, the main continents that we know today had been separated from the Pangea supercontinent of 250 million years earlier and were roughly in shapes that are recognizable today. At the time the tracks were made the current continent of North America was divided by a shallow sea that ran from the Arctic area to the current Gulf of Mexico. This sea is known as the Western Interior Seaway. Its western shore ran along the eastern area of the Rocky Mountains. The western portion of the Seaway covered the states of Texas, Colorado and Wyoming as well as much of Montana, Utah, and New Mexico. Throughout the 79 million years of the Cretaceous period the seaway rose and fell, receding from and later re-covering areas of shoreline.

Along this shoreline walked the dinosaurs. They lived in what was likely a marshy area of damp soils in which their footsteps would create massive footprints that can now be seen in several areas along what was the western boundary of the Western Interior Seaway. This western boundary now contains what is called the Dakota Group of rock which was laid down by the silts of the Western Interior Seaway.

The trackway at what is now known as Clayton Lake State Park was discovered after a large rain event in 1982. The dam which forms Clayton Lake was built in the 1950s and improved in the 1970s. The dam captures the water of the Seneca Creek which is held behind the dam. The dam is 92 feet high and 150 feet long with a broad walking path on the top. This path leads to the dam’s spillway on its northern end. This is where the dinosaur footprints may be seen. When the dam was built a spillway was cut out of the adjacent hillside so that the dam would not be damaged by heavy rain events. In that type of rain event, the lake may become filled to near the crest of the dam. The adjacent spillway allows water from the lake to be channeled around the side of the dam so that it is not over-topped by the rising water. In 1987 as the water rose it flowed over the spillway in torrents large enough to carry away the layers of rock and dirt that overlay the bottom of the spillway.

I imagine that I can see that storm and the rising water in the lake. The overflow from the lake flows across the spillway, cutting away material above the dinosaur footprints and exposing them. Now as I look out, I can see the herd of dinosaurs moving up the shore of the lake. Large hadrosaurs, believed to have been Iguanodons, slowly walk past me moving north along the shore of the Western Interior Seaway. They browse on the vegetation that grows along the shore . Some splash out into the shallows of the water to eat the submerged vegetation that grows there. A baby Iguanodon scurries past me looking around for its parent. As it passes, a crocodile, swims up through the shallows looking for a meal, perhaps something about the size of the small Iguanodon that just passed. The crocodile is too small to be a threat to the adults, but it is large enough so that as it lies in the shallows, watching, the adult Iguanodons move around it. As I stand watching, the beasts in the herd flow around me, large bulls, adolescents, females, and scurrying so as not to be stepped on a number of the baby Iguanodons. They move past me on their way up the shore of the vast inland seaway.

In the failing light of the day they continue their trek. I can barely see them through the mist and slight rain that seems to continually fall. Suddenly, ahead, I hear excited chirps and calls from the herd. A great roar is heard ,and the Iguanodons can be heard splashing in the shallows as they surge into the lake. A carnivore, a meat eater, known now as an Acrocanthosaurus, can be seen coming out of the taller vegetation farther from the shore, and moving slowly towards the herd. It moves north following the herd of herbivores, plant eaters. Soon the herd and the stalker disappear into the mists and failing light.

I find myself still standing on the walkway that surrounds the dinosaur footprints, looking down the footprint left by the Acrocanthosaurus. I am back in the present. I look out across the arena where these creatures walked over 100 million years ago.

Pictures of these dinosaurs may be found at; Acrocanthosaurus at http://www.emnrd.state.nm.us/SPD/claytonlakestatepark.html and Iguanodons at https://www.newdinosaurs.com/131_iguanodon_raul_martin/

Information on the New Mexico Clayton Lake State park may be found at http://www.emnrd.state.nm.us/SPD/claytonlakestatepark.html , https://geoinfo.nmt.edu/tour/state/clayton_lake/home.html , and https://ucmp.berkeley.edu/mesozoic/cretaceous/clayton.html .

Moon Bowl

In 1990 Science News printed an article which told of the Mimbres culture of what is now southwest New Mexico. The Mimbres people made black-on-white pottery adorned with intricate designs and mysterious animal. Of particular note in the article was a shallow bowl with the figure of a rabbit painted on the inside. According to the article the rabbit is an animal associated with the moon in numerous indigenous cultures of what is now the Southwest United States and Central America.

Upon close observation, the image of a rabbit on its hind legs can be seen in the dark areas of the full moon. Which might have led to the link between the rabbit and the moon.

The article concerned a study led by astronomer R. Robert Robbins and student Russell R Westmoreland then of the University of Texas in Austin. In studying the pottery of the Mimbres culture, they happened upon a specific bowl which pictured a rabbit “clutching” a small circular image with 23 rays. They proposed that this bowl was a record of the explosion of the supernova which created the Crab Nebula. The explosion was recorded by Chinese astronomers in the 11th century Common Era (CE). This would make the bowl, now known as the Supernova bowl, the only known record of the supernova that created the Crab Nebula outside China and Japan.

At the time I found the story intriguing and started a search for more information on stories from indigenous peoples related to a rabbit on the moon. I was also curious about the shape of the shallow bowl. It was round but quite shallow and would not be able to hold much inside, whether it was water, or grain, or sand. I was not able to find much information on either, but I was also wrapped up in my work as an engineer – and camping along the unpopulated portions of the Outer Banks of North Carolina.

Several decades later I was sitting on my screen porch at night. I might not have been in the wilderness, but I was outside enjoying a very pleasant evening. The light that entered the porch was from a single streetlight across the street. I happened to look up at several items we had hanging on the wall of the porch, one of which was a large, shallow bowl I had bought in street market in Morocco in the 1960s. We had two of these bowls hanging on the wall as they are well made and have a colorful geometric pattern. As the light from the streetlight hit the bowls at a shallow angle the side of the bowl cast a shadow across the curved depth of the bowl and created a pattern of a waxing crescent moon, as it proceeded to a full moon. I was amazed. I carefully removed the bowl from the wall and turned it so that the light of the streetlight hit it a different angles and created a shadowing affect that appeared like the changing phases of the moon.

I found this interesting and wondered how ancient people explained the phases of the moon, or whether they might have thought of the moon as a bowl. Of course, we now know that the moon is not a bowl but rather is a sphere created around the same time as the Earth. As both revolved around the Sun and each other they became more and more rounded from the effect of the rotating motion.

Several years later while looking for a space-related gift for a colleague who was retiring, I came across a “moon bowl”. It was made of metal with an acid-etched surface. It was very shallow and looked very much, in its general shape, like the Mimbres bowl I had read about so many years before. I gave the gift and told the story, or what I thought was a plausible story, of how ancient people might have used a bowl to explain the phases of the moon.

Recently, I went in search of more of these metal bowls but was disappointed to learn that the foundry in Vermont was no longer making the bowls.

But the story does not change, and now when I stand outside and look up at the night sky. I wonder what ancient people thought the moon and the stars and the wandering planets might be. Some stories have come down to us, from when those people, our ancestors, stood outside and gazed up and the night sky and marveled at its beauty.

The Science News article from 1990 may be found at; https://www.sciencenews.org/archive/astronomy-71

Dr. R. Robert Robbins remains on the staff of the University of Texas in Austin where he teaches the history and philosophy of astronomy and archaeoastronomy; and science education.

The picture of the “Supernova Bowl” below is from a copy of the Science News article. I will post a better one if I can find it.