Category Archives: Geology

Learn about Moissanite

Moissanite is an interesting gemstone that is starting to become very popular. Although it was only really introduced commercially in the last 10 years, it has been known for over 100 years. First discovered in a meteorite crater in 1893, it was not found anywhere outside of extraterrestrial origins until the 50s, and even then only tiny fragments were found in other mines.

Fortunately, moissanite is relatively easy to produce commercially. It is made by combining coal byproducts with sand and glass, and heated to over 2000 degrees. This method is used to produce large quantities of a rough form, also called carborundum. This is mainly used as an industrial abrasive.

To produce moissanite jewelry, a better quality of stone is required – however the basic process is similar. Vaporized SiC is heated and allowed to cool in a chamber containing seed crystals. This process produces very good gem quality stones in around 6 hours, and the process is much more reliable and consistent than that of producing other synthetic gems, such as lab diamonds.

Moissanite is a beautiful gemstone, but it isn’t necessarily an ideal substitute for a real diamond. Although it is nearly as hard as a diamond, it is much more brilliant and colorful. This means that it can be easily identified, particularly next to a real diamond. However that is not to say that it isn’t an amazing gem in its own right. many buyers seek out moissanite deliberately for just that reason – its fire and sparkle make it an appealing stone, that is well suited to a range of jewelry applications. Some jewelers report that younger buyers favor this stone because of its flashy, ‘blingy’ character – but at the same time, it can be used in elegant dress earrings paired with white gold.

Although moissanite is much cheaper than a diamond, it is still considerably more than it’s closest rival, cubic zirconia. But as a gem that is relatively less common, it might be worth exploring if you are in the market for something a little bit different.

Niobrara Chalk

One of the most famous formations is the Niobrara Chalk. This formation is exposed in northwest Kansas and southern Nebraska. Formations are sometimes divided into members, subsections of the formation based upon its rock type. The Niobrara Chalk has two members: the lower Fort Hays Limestone and the upper Smoky Hill Chalk. It is the Smoky Hill Chalk which is best known for its fossils.

The sediments that comprise the Niobrara Chalk were deposited in the Western Interior basin during the Late Cretaceous. At that time sea levels rose and the interior of North America was inundated by a shallow sea, the Western Interior Sea. The sea cut North America in half by spreading from the Gulf of Mexico to the Canadian Arctic. Volcanoes to the west, in what is now Utah and Nevada, spewed ash into the sea and sediments eroded from mountains along the western coast were washed into the sea by rivers. What is today Kansas was much closer to the eastern shore of the sea, a low alluvial plain, also gently washing sediment into the sea basin.

Block diagram of the Western Interior Sea

Image from Hattin, 1982.

The upper member, the Smoky Hill, was deposited from 87 to 82 million years ago, so it preserves a five million year window into the past. Elsewhere we discussed that the Cretaceous sea had a wealth of planktonic organisms. Many of those organisms had calcium carbonate-based shells and body parts, which furnished a steady supply of material to sink to the sea floor. The consistent supply of sediment, both from land and sea, and conditions at the sea floor allowed for the excellent preservation of animals. Those that died and sank to the bottom were rapidly covered by the rain of sediment and entombed until today.

And the diversity of organisms preserved is amazing. In almost every museum with fossils that I have been in, I recognize fossils from Kansas. Giant marine reptiles (mosasaurs and plesiosaurs), flying reptiles (pterosaurs), great toothy fishes, large turtles, and toothed diving birds have all been found. Each of these groups has a very interesting story to share, and we will explore many of them here. An extensive website on fossils from the Niobrara Chalk can be found at OceansofKansas.com.

UTM

In a couple of previous posts we have examined latitude and longitude in some detail, and explored in what format the numbers might be displayed on your handheld GPS unit. Here we will explore another commonly used coordinate system: UTM.

Latitude and longitude work well, but since they are all based upon circles, and because degrees are divided into groups of 60, the calculations required to work with them are unwieldy. It is frequently useful to have coordinates based upon plane rectangular geometry in our normal base 10 system. This can work well if the area in question is not too large, because then we can discount the curvature of the Earth. Over just a section of the Earth, the curve does not make a huge difference in error.

In order to do this, we must “flatten” the Earth to a plane, and when we do we can use the Cartesian coordinates that we all used in high school geometry class. It would be like flattening the peel of an orange. If you try to flatten the whole peel it makes a very irregular shape. But if you flatten a small piece it does fine. Then you can think of the x and y axes as east-west and north-south.

Cartesian coordinate system illustrated

The familiar Cartesian coordinate system showing how points can be assigned a distance along two axes from the origin point.

As you recall, every point on this plane can be described by two coordinates, one along each axis. And you can see in the  illustration that some of the points have negative values with respect to the origin (point 0,0). However, we can control how we place the coordinate system, and with the origin point outside of our area of interest all the points can be positive (east, north)—in the upper right-hand quadrant.

State of Kansas laid on top of a Cartesian coordinate form

The State of Kansas placed on the rectangular grid so that every point in the state will be positive with regard to the origin.

UTM coordinates, or Universal Transverse Mercator coordinates, are a rectangular plane system in metric units. Cartographers have taken swaths of each state and mathematically flattened them into a plane, assigned an origin southwest of each section, and laid out the resulting grid. Some of the smaller states are covered in a single swath, but the larger states must be broken into several zones so that the curvature of the Earth does not distort each map too much.

So, UTM coordinates have two components: their easting and northing values from the origin point in meters, and which state zone you are referring to. You can see a map of the zones here.

I have used UTM coordinates to good effect in my scientific work. When mapping a paleontological excavation, for example, we make all measurements in metric units. Since we are already measuring in metric units, every point in the dig site can easily be assigned its real-world UTM coordinate, instantly relating all points in the dig to any other point on the globe.

This means we can accurately and quickly plot the location of any fossil site, or even individual fossils, on a real-world map.

Related posts:
Recommended handheld GPS units
handheld GPS basics
Basic features in a handheld GPS
Geocaching
Mapping the Pratt Mammoth

What is paleontology

What questions fall within the purview of “Paleontology”?

Quite a wide variety, it turns out, because paleontology is the study of prehistoric life – the exploration of the entire history of life. Since 99.9% of all species that existed are now extinct, that is a lot of biodiversity. The science is multifaceted and diverse because the topic is equally diverse.

Because of the connections with geologic time and rock formations as the context of fossils, most paleontology classes are offered through geology programs at universities. I LIKE teaching introductory courses in geology because I find that people frequently end up taking geology in college as a last resort. Students generally are required to take a science class with a laboratory and they too frequently review their options without much enthusiasm. They took biology in high school and did not like it then, so want to stay away from that now. Chemistry and physics sound like a lot of math, so that leaves geology, they reason.

Fossil collecting in western Kansas. A partial mosasaur skeleton is visable in the middle foreground.

Fossil collecting in western Kansas. A partial mosasaur skeleton is visible in the middle foreground.

On the first day of geology class I like to point out that the study of the Earth and its history involves biology, chemistry, and physics, so we will cover them all. There is usually a little moan from the class at this, and I enjoy my moment of sadism. Paleontology in particular incorporates biology and geology to a very high degree, because to study fossils you have to fully understand the animals as well as the history that you can read from the rock record.

So could we come up with a classification, not of fossils, but of paleontologists?

Since the topic is so multifaceted the science falls naturally into several key areas. For example, individual paleontologists tend to be more oriented toward either geology or biology. The first group might be more interested in the animals themselves: how did they live; how did they move and capture prey; how did they relate to other organisms in their environment.

The second group might be more interested in what the animals can tell them about the Earth’s history: what do the fossils tell us about the movement of plates over the Earth’s surface through time; when did different animals live in geologic time so we can estimate the age of rocks; that sort of thing.

Of course, this is an over simplification.

Paleontologists can also be classified by which group of organisms they work with. Is it plants (maybe fossil forests made of ferns), or invertebrates animals — marine or terrestrial – ranging from the largest squid ever known to fossil spiders, or maybe vertebrate animals.

A lot of the people I know are paleontologists, and they tend to be people with diverse interests, often ending up doing a bit of all of it. For example, many years ago I worked on a fossil locality in southwestern Kansas that included plant, invertebrate, and vertebrate fossils. Having all the groups of organisms was critical to interpreting a much fuller picture of the ancient environment there than any one of the groups alone could have provided.

As a paleontologists I must be a “jack of all trades,” and that is one of the things I love most about it.

Other interesting facts can be found here at Boneblogger. Enjoy.

Bonnerichthys

In modern oceans, the very largest organisms specialize in filter feeding, or living on the very small plankton in the water. (Read more about the filter feeding niche). Up until now, it has appeared to researcher that during the Age of Dinosaurs, when the oceans were dominated by large, toothy reptiles, there were no marine animals specializing in the niche of large-bodied filter feeding, despite ample evidence that the oceans were rich in planktonic resources.

However, this niche was in fact filled during the Mesozoic as demonstrated in a recent paper in the journal Science (Friedman et al., 2010). Turns out that several species of fish did specialize in filter feeding, and they too grew quite large. Most of the specimens were already sitting in drawers in museums, having been misunderstood for many years, until Friedman and his colleagues re-evaluated them.

For example, one species has been known for over 100 years—having been named by E. D. Cope in 1873 as ‘Portheus’ gladius from a specimen collected from the Niobrara Chalk formation in western Kansas. The Niobrara Chalk was deposited during the Late Cretaceous period (see a geologic time scale). The species has a long and complex taxonomic history, mostly of interest to professionals, but it does clearly show that many scientists reviewed the fossil material and scratched their heads in wonder about this strange set of fossils.

Friedman and his colleagues have finally put the pieces together, and it fills in much about the history of life in the oceans. They have created a new genus in which to place the species, so now it is known as Bonnerichthys gladius. The genus was named for the Kansas fossil-collecting family that collected the most complete specimen found to date.

Bonnerichthys would have been about 20 to 25 feet in length with a huge, gaping mouth. You can see an artist’s reconstruction of Bonnerichthys at Oceans of Kansas. And you can listen to an interview with Matt Friedman at NPR.

This discovery opens up a whole new understanding of the paleoecology of the Mesozoic oceans, and shows that filter feeding was utilized for at least 100 million years longer as a major life strategy than previously recognized.

FRIEDMAN, M., K. SHIMADA, L. MARTIN, M. J. EVERHART, J. LISTON, A. MALTESE, AND M. TRIEBOLD. 2010. 100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas. Science, 327:990-993.