Studded Cilia

What beachcombers find is the test or skeleton, which is made up of interlocked plates. In life, these tests are studded with short spines that, in turn, are covered with small, hairlike structures called cilia, which make living sand dollars look fuzzy.

Using Cilia to Move & Eat

Living sand dollars use the cilia to move across the ocean floor. They burrow within the ocean floor’s sand and use the cilia to direct food particles to their mouth. A sand dollar’s mouth is located at the bottom center of the test. Sand dollars have distinctive five-rayed stars on top called petals. These petals are used for gas exchange or respiration.

Fossil History

In the history of life, sand dollars are young. Their close relatives, the sea urchins, have a long fossil record. For instance, my collection of ocean fossils includes 300 million-year-old spiny sea urchins. In the Age of Dinosaurs, during the Mesozoic Era, sea urchins became especially common. Sand dollar ancestors began diverging from other echinoids during this time. However, it wasn’t until 65 million years ago that true sand dollars appeared, during the Paleocene, or the first epoch of the “Age of Mammals” in the Cenozoic Era.

Sand dollars have done well, with 250 living species. Their rigid tests, their tendency to live in large colonies and to burrow into sandy or muddy seafloors are all perfect for fossilization. Where you find one fossil sand dollar, you tend to find hundreds!

This Rock & Gem Kids story about fossil sand dollars previously appeared in Rock & Gem magazine. Click here to subscribe! Story and photos by Jim Brace-Thompson.

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As our good Mother Earth orbits its Sun, we come into regular collision courses with leftover debris from comets, asteroids, and other residents of our solar system that float about in our general neighborhood. Some of these debris clouds have resulted in annual meteor showers streaking through the atmosphere, and one good show is coming up soon!

The Perseids, associated with the comet Swift-Tuttle, is said to be among the most prolific of all annual meteor showers. The shower is called the Perseids because, to the casual observer, the meteor streaks seem to originate from the constellation Perseus. The debris stream known as “the Perseid cloud” is composed of particles left behind by Swift-Tuttle during its 133-year orbit around the Sun.

Although usually starting in mid to late July, the shower peaks in early August, with something like 45 to 90 meteor streaks per hour across the night sky. The best time for viewing is said to be during pre-dawn hours, from midnight to sunrise. This year, the shower should peak with a maximum number of streaks during the pre-dawn hours of August 12, 2021, but be on the lookout on August 11 and 13, as well.

It’s almost always a fine show, even in light-polluted skies. Watch for it!

The post The Perseid Meteor Show Is Coming – Watch for It! first appeared on Rock & Gem Magazine.

The story reads like an exciting detective yarn complete with wartime drama, a deathbed confession, and a name just made for newspaper headlines.

A wonderfully complete skull was unearthed in a riverbank and hidden from view in China during forced labor to build a bridge over the Songhua River under Japanese occupation leading up to World War II. The young Chinese laborer who made the find had wrapped and lowered it into a well to hide it from occupying forces. As he lay dying, nearly 90 years later, he finally told his story to his grandchildren, who prefer to remain anonymous.

Now the skull has been unearthed once again in a series of papers in the journal The Innovation, where paleontologist Qiang Ji and colleagues have named it Homo longi. Translation? “Dragon Man”!

Per their analysis, this fossil human is a step closer to modern Homo sapiens than the Ice Age Neanderthals, who have long been considered our closest relative on the human family tree.

While the Chinese team has given the skull a whole new taxonomic designation, other scientists suspect that Dragon Man may represent the first nearly complete skull of a group of ancient hominins known as the Denisovans, or “an extinct cousin of the Neanderthals.” Up to now, Denisovans chiefly have been known from bits and pieces of bone, teeth, and DNA, as well as the stone tools they left behind in various sites across Asia and Siberia. In the journal Science, some are saying this skull “may reveal the long-sought face of a Denisovan” from between 183,000 and 309,000 years ago.

Is it so? Stay tuned! This detective yarn is just beginning.

The post The Exciting Case of China’s ‘Dragon Man’ first appeared on Rock & Gem Magazine.

They say diamonds are judged by the 4Cs: color, clarity, cut, and carat weight. But when a new diamond is dug up, all everyone seems to focus on is carats. And so it is with the latest big discovery out of Botswana.

Weighing in at 1,174 carats, this stone is said to be the third-largest recorded gem-quality diamond ever found. Photos of people holding it show it to be as large as a juice glass, or big enough to “fill the palm of a large hand,” per one report. Its exact dimensions, per a company press release, are 77x55x33mm.

The diamond was recovered after material mined from a kimberlite deposit went through a primary crusher, and it is believed that the original stone may have weighed in excess of 2,000 carats before the rough material entered the crusher. Why do they believe this is so? Three other diamonds with very similar characteristics were recovered at the same time weighing 471 carats, 218 carats, and 159 carats. All are believed to have been part of one stone.

The stone is a clear or “white” diamond. It was discovered on June 12, 2021, by the Lucara Botswana division of Lucara Diamond Corp. of Canada at the Karowe Diamond Mine and was subsequently presented to the Botswana government in a July 7 ceremony that included President Mokgweetsi Masisi. By July 19, the stone was residing in Antwerp, the diamond processing capital of the world, to be examined, analyzed, and valued over the next four to six months. (Preliminary estimates put the value of the stone at tens of millions of dollars.) From Antwerp, it will head to New York City as part of a world tour before the stone is ultimately cleaved into smaller cut stones. An official name for the diamond is yet to be chosen.

Botswana has eclipsed South Africa as the leading diamond producer on the African continent. In fact, it is said that Botswana alone accounts for six of the top ten raw diamonds ever discovered! By the way, this latest find follows close on the heels of the June 1 discovery of a 1,098 carat diamond by the Botswana diamond firm Debswana. Ever-so-briefly, it was the third largest diamond ever found.

For the record, the largest raw diamond ever found? That would be the 3,106-carat Cullinan Diamond dug up in South Africa back in 1905 and cut into pieces to join the Crown Jewels of Great Britain. The second-largest diamond? A 1,758-carat stone called the Sewelô also found in Botswana’s Karowe Diamond Mine in 2019.

The post Botswana Produces the World’s Third-Largest Diamond first appeared on Rock & Gem Magazine.

An article in a recent issue of the journal Science calls it “the hidden crisis beneath our feet.”

As populations increase and demand more resources, and climate warms and dries, essential groundwater is rapidly depleted! In the American Southwest, gallows humor has it that, one day soon, someone in Phoenix is going to hear a loud dry sucking sound as the last drops of well water dribble from a faucet.

But it’s not really funny at all. Some 96 percent of our unfrozen freshwater is stored in underground aquifers, where we access it via wells. Researchers at the University of California, Santa Barbara, have compiled a huge database of some 39 million wells in 40 countries on every continent except Antarctica. Their results reveal that wells supplying drinking water to billions of people and water for agricultural irrigation worldwide are at risk of running dry in places where water tables are declining significantly. Indeed, at many places wells already have run dry.

Just dig wells deeper into the aquifers? Not so easy, say the researchers, Scott Jasechko and Debra Perrone. Costs of going deeper are high, making it impractical in poorer regions. Plus, the quality of the water often declines with depth.

Because aquifers often cross beneath state and national borders, a coordinated and cooperative effort must be made to avoid the overexploitation of this essential resource and—in the face of climate change—to maintain it in a sustainable way such that no one in Phoenix need ever hear that great sucking sound at the faucet.

Author: Jim Brace-Thompson

Jim began and oversees the AFMS Badge Program for kids and has been inducted into the National Rockhound & Lapidary Hall of Fame within their Education Category.
Contact him at jbraceth@roadrunner.com.

 

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]]> https://www.rockngem.com/sounding-out-beneath-the-sea-for-the-next-big-one-in-the-pacific-northwest/ Fri, 23 Jul 2021 11:00:25 +0000 https://www.rockngem.com/?p=14899 By Jim Brace-Thompson Deep down far beneath the waves of the ocean lapping the Pacific Northwest is a gash some 810 miles long referred to as the Cascadia subduction zone. There, the Juan de Fuca Plate of oceanic crust (along with the much smaller associated Explorer Plate to the north and Gorda Plate to the […]

The post Sounding Out Beneath the Sea for the Next ‘Big One’ in the Pacific Northwest first appeared on Rock & Gem Magazine.

]]> By Jim Brace-Thompson

Deep down far beneath the waves of the ocean lapping the Pacific Northwest is a gash some 810 miles long referred to as the Cascadia subduction zone. There, the Juan de Fuca Plate of oceanic crust (along with the much smaller associated Explorer Plate to the north and Gorda Plate to the south) is taking a deep dive beneath the North American Plate. As it does so, it has generated huge stratovolcanoes across northern California, Oregon, Washington, and British Columbia—Mount St. Helens, Mount Rainier, Mount Hood, and Mount Shasta, to name but a few.

The plate boundary also generated one of the greatest recorded earthquakes in North America back in 1700. Clocking in at an estimated magnitude 9.0, it not only shook up the Pacific Northwest but also sent a tsunami rolling clear to Japan!

However, in recent times quakes here have been few and far between. “It’s just way, way, way too quiet” down there, says marine geologist Chris Goldfinger (Oregon State University) as reported in the July 2, 2021, issue of the journal Science. Earth scientists aboard the research vessel Marcus G. Langseth hope to learn why.

On a two-month mission, the ship is currently zig-zagging the coast with an airgun, blasting sound waves down into the crust and capturing echoes via hydrophones and other receivers positioned both on the ocean floor and inland along the coast. Those echoes are helping earth scientists and seismologists map the underground terrain of the Cascadia subduction zone at an unprecedented level of detail.

If all goes well this summer, by the end of the voyage of the Langseth, we should have plenty of data to help map the Cascadia subduction zone to help shed light on subduction zone dynamics in general and to help tell us: Is the next Big One coming?

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Author: Jim Brace-Thompson

Jim began and oversees the AFMS Badge Program for kids and has been inducted into the National Rockhound & Lapidary Hall of Fame within their Education Category.
Contact him at jbraceth@roadrunner.com.

 

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]]> https://www.rockngem.com/coleville-earthquake-sends-rocks-flying-across-the-road/ Wed, 21 Jul 2021 12:24:18 +0000 https://www.rockngem.com/?p=14880 By Jim Brace-Thompson On the afternoon of July 8, 2021, clouds of dust rose from mountains, and boulders rained down on a highway in the biggest earthquake to hit California since the magnitude 6.4 and 7.1 Ridgecrest quakes of July 4 and 5, 2019. This latest quake registered 6.0. It was centered south of Lake […]

The post Coleville Earthquake Sends Rocks Flying across the Road first appeared on Rock & Gem Magazine.

]]> By Jim Brace-Thompson

On the afternoon of July 8, 2021, clouds of dust rose from mountains, and boulders rained down on a highway in the biggest earthquake to hit California since the magnitude 6.4 and 7.1 Ridgecrest quakes of July 4 and 5, 2019. This latest quake registered 6.0. It was centered south of Lake Tahoe near California’s border with Nevada in the town of Coleville.

Motorists on US 395 shot cellphone videos of huge boulders rolling onto the roadway. Rocks hit several cars, and a 40-mile stretch was closed for an hour. Meanwhile, another rockslide hit a Kampgrounds of America.

Fortunately, there were no reports of death or serious injury from either rockslide.

Still, magnitude 6.0 is nothing to sneeze at. The shaking was felt far and wide in places like Carson City and Reno in Nevada, all across California’s Central Valley, and even the San Francisco Bay area and Las Vegas. More than 23,000 reports flooded the website of the U.S. Geological Survey (USGS), and as many as 100 aftershocks were not long in following. At least six registered magnitude 4.0, and one was as large as 5.2. One expert warned folks to expect aftershocks for days. In the immediate vicinity of the epicenter, cups and dishes fell from shelves, bottles smashed to floors, tables and chairs bounced, ceiling lights and window blinds swayed, and water in swimming pools sloshed in big waves. Even in Sacramento, high-rise buildings swayed and were immediately evacuated.

Geologists commonly refer to this region as “Walker Lane” and note that it is earthquake-prone due to the many faults in the region.

In fact, a magnitude 6.1 quake hit not far away along the Antelope Valley fault in 1994. Per Austin Elliott of the USGS, “this is a classic place geologists go to study earthquakes.” Any geologist there to study on July 8 got a classic textbook lesson they’ll surely remember for the final exam!

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Author: Jim Brace-Thompson

Jim began and oversees the AFMS Badge Program for kids and has been inducted into the National Rockhound & Lapidary Hall of Fame within their Education Category.
Contact him at jbraceth@roadrunner.com.

 

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]]> https://www.rockngem.com/rg-kids-gemstone-carving/ Tue, 13 Jul 2021 14:51:15 +0000 https://www.rockngem.com/?p=14793 By Jim Brace-Thompson One enjoyable form of lapidary arts is carving. I’m not talking about a sculpture of the sort that Michelangelo crafted from 10- or 20-foot slabs of marble, nor huge national monuments like the Lincoln Memorial or Mount Rushmore. Rather, think of small sculptures that can fit into the palm of your hand […]

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]]> By Jim Brace-Thompson

One enjoyable form of lapidary arts is carving. I’m not talking about a sculpture of the sort that Michelangelo crafted from 10- or 20-foot slabs of marble, nor huge national monuments like the Lincoln Memorial or Mount Rushmore. Rather, think of small sculptures that can fit into the palm of your hand or even smaller pieces that might be incorporated into necklaces or wire-wrapped jewelry.

Carving hard rocks such as agate, jasper, or jade requires fairly expensive tools and machines such as a flexible shaft Foredom or Dremel with diamond bits and carving points, a gem lathe or fixed-shaft spindle, or more. Besides the expense involved in acquiring such machines and their associated bits, carving these harder rocks requires instruction with an experienced mentor and lots of practice.

Also, rough semi-precious gemstones such as jade or lapis lazuli don’t come cheap! Still, the pay-off and reward in the form of a beautiful, gleaming work of art are worth the expense and the effort.

But not all carving requires expensive equipment or materials. For instance, soft-stone carving with commonly available and inexpensive rocks such as alabaster, soapstone, marble, or travertine can be accomplished using simple hand tools. These include knives, scribes, files, sanding boards, various grits of wet-and-soft sandpaper, and polished-infused pieces of leather or cotton flannel.

Whether you opt for hard-stone carving with expensive machinery and high-priced rough stones or for soft-stone carving with hand tools and easily acquired rocks, you will be able to take great pride and satisfaction in transforming somewhat dull, ordinary rocks from nature into shining and dazzling works of art that are wonders to behold!

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Author: Jim Brace-Thompson

Jim began and oversees the AFMS Badge Program for kids and has been inducted into the National Rockhound & Lapidary Hall of Fame within their Education Category.
Contact him at jbraceth@roadrunner.com.

 

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In addition, we invite you to consider subscribing to Rock & Gem magazine. The cost for a one-year U.S. subscription (12 issues) is $29.95. Learn more >>>

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]]> https://www.rockngem.com/volcanos-continue-capturing-headlines/ Fri, 25 Jun 2021 13:43:02 +0000 https://www.rockngem.com/?p=14667 By Jim Brace-Thompson In the first half of 2021, I reported on one volcanic eruption after another. Well, it looks like I’ll be continuing to report on volcanoes so long as I’m writing these articles. For instance, here are two recent reports that appeared in the scientific literature… Being able to predict when a volcano […]

The post Volcanoes Continue Capturing Headlines first appeared on Rock & Gem Magazine.

]]> By Jim Brace-Thompson

In the first half of 2021, I reported on one volcanic eruption after another. Well, it looks like I’ll be continuing to report on volcanoes so long as I’m writing these articles. For instance, here are two recent reports that appeared in the scientific literature…

Being able to predict when a volcano might blow its top is of major import for public safety when volcanoes are near populated areas. When it comes to the difficult science of predicting a volcanic eruption, earth scientists might measure substantial increase in earthquakes and other seismic activity and/or they might use measurements of deformation and bulging in the earth around a volcanic cone.

Writing in the journal Nature Geoscience, a team led by Társilo Girona (University of Alaska Fairbanks) has identified a new way to predict and warn of a potential volcanic eruption, giving earth scientists and public safety officials a new arrow in their quiver. Namely, they have cued into “large-scale thermal unrest,” or subtle but long-term increases in surface heat that can now be detected via Earth-monitoring satellites.

In other news, Mount Nyiragongo in the Democratic Republic of the Congo continues to wreak havoc after an initial eruption that killed more than 30 people. Although its major eruptive events and fast-moving lava flows have stopped, some 400,000 evacuees remain forbidden to return home as small earthquakes continue and dangers remain from toxic gases. Mount Nyiragongo is a classic and poignant example of the need to develop ever-better ways to monitor and predict volcanic eruptions.

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Author: Jim Brace-Thompson

Jim began and oversees the AFMS Badge Program for kids and has been inducted into the National Rockhound & Lapidary Hall of Fame within their Education Category.
Contact him at jbraceth@roadrunner.com.

 

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In addition, we invite you to consider subscribing to Rock & Gem magazine. The cost for a one-year U.S. subscription (12 issues) is $29.95. Learn more >>>

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]]> https://www.rockngem.com/a-sea-without-sharks/ Fri, 25 Jun 2021 13:37:53 +0000 https://www.rockngem.com/?p=14669 By Jim Brace-Thompson For hundreds of millions of years, sharks and oceans have gone together like salt and pepper, ebony and ivory, bread and butter, bananas and monkeys, or whatever your favorite analogy for two things that, well, just seem to belong together. So imagine: A sea without sharks? Apparently, it nearly happened back in […]

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]]> By Jim Brace-Thompson

For hundreds of millions of years, sharks and oceans have gone together like salt and pepper, ebony and ivory, bread and butter, bananas and monkeys, or whatever your favorite analogy for two things that, well, just seem to belong together. So imagine: A sea without sharks?

Apparently, it nearly happened back in the early Miocene Epoch!

Per a research report by Elizabeth C. Sibert (Harvard University) and Leah D. Rubin (College of the Atlantic) in the June 4, 2021 issue of the journal Science, populations of pelagic sharks were decimated by an extinction event that has only now been fully recorded, recognized and appreciated thanks to detailed studies Sibert and Rubin have made of deep-sea sediments.

The pelagic zone is defined as the so-called “open ocean.” Sibert and Rubin estimate that 19 million years ago sharks in the open ocean declined in morphological diversity by 70 percent and in overall population abundance by as much as 90 percent! And it all seems to have happened within less than 100,000 years, or a mere blink-of-the eye, geologically speaking. Following this extinction event, sharks never recovered their prior diversity.

Per the report, the proximate cause of the extinction event is something of a mystery but the event itself indicates “the early Miocene was a period of rapid, transformative change for open-ocean ecosystems.”

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Author: Jim Brace-Thompson

Jim began and oversees the AFMS Badge Program for kids and has been inducted into the National Rockhound & Lapidary Hall of Fame within their Education Category.
Contact him at jbraceth@roadrunner.com.

 

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