Cobalt Red

I recently read an interesting book, Cobalt Red, about cobalt mining in the Congo (a country that has been cruelly exploited by the west for centuries). The Katanga Region of the Congo in Africa holds more cobalt than the rest of the planet combined (as well as a host of other metallic ore minerals).

Why does the Congo hold so much cobalt? It's complicated. Here's a paper with the details if you're up on your geochemistry. The bottom line is that around 4-5 million years ago (the Pliocene Epoch), near surface rocks were exposed to weathering under just the right pH conditions to form a mineral called heterogenite (CoOOH), an ore of cobalt. Being near the surface, in heavily weathered material, the mineral is relatively easy to mine by hand.

Why is cobalt important? It's critical for making the cathodes (positive terminals) of lithium-ion batteries (which are in everything from cell phones to Teslas). China, South Korea, and Japan produce almost 90% of the world's lithium-ion batteries and they all get their cobalt from the Congo.

While companies that use lithium-ion batteries like Apple, Samsung, and Tesla tout how socially responsible they are on their websites, the reality of cobalt mining in the Congo is that it's done under slave-like conditions by "artisanal miners" as young as 12 who work under horrific conditions destroying their health and the landscape for a pittance while consumers in the U.S. feel virtuous for being "green" and multinational companies make billions.

The author is a U.K. professor who's research specialty is modern slavery. He faced real dangers traveling through the Congo and visiting these mines since the government there and the primarily Chinese mine owners resort to violence and murder to keep the status quo. Reading the comments of the miners is heartbreaking - "Here it is better not to be born." It's a depressing but important read.

What on Earth is a Urolite?

Every heard of a urolite? Me neither. What about a coprolite? I suspect more people have probably heard of these.

Coprolites are fossilized feces or poop. There's nothing disgusting about them, the material has been completely mineralized and it's no worse than handling a rock (although when I pass one around the geology lab, some students are very reluctant to even touch it). Here are a couple of samples I have in my lab (I don't know what animal left these coprolites).

Coprolites are ichnofossils or trace fossils in that they record a trace of an organism's activity (rather than a fossil of the organism itself). Paleontologists find coprolites useful since they can often provide information about the animal's digestive system and diet - below are microscopic views of coprolites from a scientific paper studying the diet of a group of herbivorous dinosaurs.

I happened to stumble on a paper recently that introduced me to urolites. Urolites are another type of ichnofossil that are formed from sediments disturbed by the urine stream of an animal (hence the "uro" part of the name). In the case of the paper I read, urine streams from early Cretaceous Period dinosaurs in Brazil. Here's a picture from the paper of some urolite examples.

and a drawing illustrating the concept.

The authors said these fossils compared well to similar features formed by modern ostrich urinating in sand. They also claimed that this is the first direct evidence of liquid waste elimination by dinosaurs.

While not the sexiest of fossils, it's always neat to see what we can see and learn by careful observation of the world around us.

Mudcracks & Ripple Marks

Back in 1788, Scottish polymath and geologist James Hutton, in his seminal work titled Theory of the Earth, came up with a concept in geology that came to be known as uniformitarianism.

The basic assumption in uniformitarianism is that we can interpret Earth's past history by assuming that the processes we see operating today were essentially the same processes operating in the Earth's past. This concept was later summarized by the memorable phrase "The present is the key to the past." While not always strictly true, in some ways the ancient Earth was different from the modern Earth, it is often a good guiding principle.

As an example, I took a picture in summer 2022 of a place called Duck Pond in the Mohonk Preserve on the Shawangunk Ridge near New Paltz. At the time, there was an issue with the dam impounding the pond and water levels were very low exposing the bed of the pond in places. The summer sun dessicated the mud forming mudcracks.

Here's a picture from the same month and year as the previous shot but taken in Sojourner Truth State Park in Kingston. This is a slab of 420 million year old rock (Late Silurian Rondout Formation) showing what appear to be preserved mudcracks. The concept of uniformitarianism tells us that it's reasonable to assume that this structure in the rocks are, in fact, mudcracks and formed in a similar way to those we find in the modern world.

And, importantly, these mudcracks tells us something about the paleoenvironment that existed here in Ulster County in the geologic past. It's not the whole picture, because mudcracks can form in different environments (a drying up lake bed as above or perhaps a muddy tidal flat on a shoreline) but other features in the rock, such as fossils, might help us figure that out.

Similarly, one can look at ripples in sand, like these in shallow ocean water I took at Ocracoke Island in North Carolina a few years ago.

Then we can look at 420 million year old (also Late Silurian Rondout Formation but hear High Falls, NY) rock and find preserved ripple marks.

Here's another picture of ripple marks from the Mohonk Preserve in the Shawangunks in even older rock (Mid-Ordovician Martinsburg Formation). I didn't take this picture, it's from a 2009 New York State Geological Association Field Guide (although I was on this trip).

Once again, the interpretation is that these ripple marks preserved from hundreds of millions of years ago in rocks formed by the same physical processes that form ripple marks in sand today - back and forth currents of water or wind.

These types of features are called sedimentary structures - essentially fossils of features formed in sediments and then preserved in rock as the sediments lithify. They are invaluable features for attempting to unravel the ancient geological history of an area like the Hudson Valley.

Yule

Merry Christmas for those who celebrate. While I grew up with Christmas, I don't find it particularly meaningful as an adult (although I still observe it for my wife and stepson). The winter solstice is, in many ways, a far more interesting seasonal event for me. Occurring last Thursday, December 21, at exactly 10:27 pm, it marks the point of maximum tilt of the Northern Hemisphere away from the Sun in our yearly orbit.

Many people, incorrectly, assume that the change in seasons has to do with our distance from the Sun. This is incorrect as the Earth is closest to the Sun (perihelion) on January 2, 2024 (aphelion, the furthest point, is six months later in early July). The seasons are due to the tilt of the Earth's axis as it orbits the Sun. When the Northern Hemisphere is tilted away from the Sun, the sunlight at our mid-latitudes can't reach halfway around the Earth leading to a 9 hour day here in Ulster County, NY. In addition, the Sun is at a lower angle in the sky (about 25º altitude) meaning the incoming solar energy (insolation) is smeared out more than in the summer when the Sun is higher in the sky (around 70º of altitude with 15 hours of daylight in late June). It's the tilt, not the distance that causes the seasons.

There's a reason why almost all ancient cultures (at least in the mid-latitudes) observed the solstices - they are real events with a real impact on our lives. They especially impacted ancient people since solstices and equinoxes, along with the cycle of phases of the Moon, defined all early calendars (and even some religious calendars today).

I always try to mark the winter solstice with a fire in my backyard fire pit after the Sun goes down. Depending on the outside temperature, some friends or family may or may not join me. For me, like my northern European ancestors, the winter solstice is a time to celebrate as it marks the turning point where the days start to get fractionally longer again even though the worst parts of winter are yet to come. In ancient times, it used to be, and still should be in my opinion, the official New Year's Day. January 1 is an artificial construct due to political considerations in the Roman Empire.

The decreasing hours of daylight in the winter really gets to me. I have to always make an effort to get outside and get some sunlight during these shorter days - something difficult to do when I sometimes find myself inside working for most of those daylight hours and the persistently cloudy Hudson Valley winter days.

So, no geology in today's blog post (although talking about the seasons is basic Earth science) but some of my outdoor winter excursions may well be to geologic locales for future posts!