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kottke.org posts about geology

What’s under the trees? LIDAR exposes the hidden landscapes of forested areas.

posted by Jason Kottke   Dec 01, 2017

WA LIDAR Geology

The Washington State Geological Survey is using LIDAR technology to study the geology of the land hidden under forested areas of the state. LIDAR is like radar, but instead of bouncing radio waves off of objects to detect their distances, you use lasers. When you shoot laser light at a forested area, most of it is reflected back by the trees. But some of it reaches the ground, so by measuring the light that’s reflected back from the lowest point, you get a very accurate map of the bare earth, sans nature. Using the LIDAR maps, they can study the course changes in rivers, landslides, volcanic lava flows, earthquake faults & fault zones, tsunami inundation zones, and glaciers.

The beautiful photo at the top is a LIDAR image of the Sauk River and all its current and former channels…the bluish tint makes it look like an x-ray, which it pretty much is. It also reminds me of the meander maps of the Mississippi River made by Harold Fisk for the US Army Corps of Engineers.

Here are two images of Bainbridge Island:

WA LIDAR Geology

WA LIDAR Geology

The LIDAR image clearly shows a horizontal earthquake fault scarp that’s completely hidden by the ground cover.

These two images are of drumlins left behind by a glacier:

WA LIDAR Geology

WA LIDAR Geology

Again, the LIDAR image shows the movement of a long-gone glacier with stunning clarity compared to the satellite photo with ground cover.

A Tapestry of Time and Terrain

posted by Jason Kottke   Nov 09, 2017

Tapestry Time Terrain

A Tapestry of Time and Terrain is a map from the USGS that shows the topology and ages of rock underneath the surface of the United States. The age scale on the right is difficult to read unless you download the full 45Mb PDF version, but it goes from Precambrian (2.6 billion years ago) at the bottom to more-or-less the present day at the top.

Through computer processing and enhancement, we have brought together two existing images of the lower 48 states of the United States (U.S.) into a single digital tapestry. Woven into the fabric of this new map are data from previous U.S. Geological Survey (USGS) maps that depict the topography and geology of the United States in separate formats. The resulting composite is the most detailed and accurate portrait of the U.S. land surface and the ages of its underlying rock formations yet displayed in the same image. The new map resembles traditional 3-D perspective drawings of landscapes with the addition of a fourth dimension, geologic time, which is shown in color. This union of topographic texture with the patterns defined by units of geologic time creates a visual synthesis that has escaped most prior attempts to combine shaded relief with a second characteristic shown by color, commonly height above sea level (already implicit in the shaded relief). In mutually enhancing the landscape and its underlying temporal structure, this digital tapestry outlines the geologic story of continental collision and break-up, mountain-building, river erosion and deposition, ice-cap glaciation, volcanism, and other events and processes that have shaped the region over the last 2.6 billion years.

(via @robgmacfarlane)

Decoding the geometry, geology, and astronomy of Stonehenge

posted by Jason Kottke   Jun 28, 2017

Vox’s Joss Fong assembles a scale model of Stonehenge and explains some of the ancient monument’s geometry, the geology of the stone it’s built from, and the its possible astronomical significance.

Stonehenge is a popular destination for summer solstice celebrations because the 5,000-year-old monument points toward the summer solstice sunrise on the horizon. However, it also points to the winter solstice sunset in the opposite direction and there’s good reason to believe that this may have been the more important alignment for the Neolithic people who built Stonehenge. We investigate by constructing a tiny model of the Stonehenge monument.

How the Cretaceous coastline of North America affects US presidential elections

posted by Jason Kottke   Oct 20, 2016

2012 Election Map

That’s a portion of the 2012 US Presidential election map of the southern states broken down by county: blue ones went Barack Obama’s way and counties in red voted for Mitt Romney.

But let’s go back to the Cretaceous Period, which lasted from 145 million years ago to 65 million years ago. Back then, the coastline of what is now North America looked like this:

Cretaceous Coast

Along that ancient coastline of a shallow sea, plankton with carbonate skeletons lived and died in massive numbers, accumulating into large chalk formations on the bottom of the sea. When the sea level dropped and the sea drained through the porous chalk, rich bands of soil were left right along the former coastline. When that area was settled and farmed in the 19th century, that rich soil was perfect for growing cotton. And cotton production was particularly profitable, so slaves were heavily used in those areas.

McClain, quoting from Booker T. Washington’s autobiography, Up From Slavery, points out: “The part of the country possessing this thick, dark and naturally rich soil was, of course, the part of the South where the slaves were most profitable, and consequently they were taken there in the largest numbers.” After the Civil War, a lot of former slaves stayed on this land, and while many migrated North, their families are still there.

The counties in which slave populations were highest before the Civil War are still home to large African American populations, which tend to vote for Democratic presidential candidates, even as the whiter counties around them vote for Republicans. The voting pattern of those counties on the map follows the Cretaceous coastline of 100 million years ago — the plankton fell, the cotton grew, the slaves bled into that rich soil, and their descendants later helped a black man reach the White House.

A robotic rocks sorter

posted by Jason Kottke   May 23, 2016

Jller is a machine that sorts stones from a specific river according to their geologic age.

The machine works with a computer vision system that processes the images of the stones and maps each of its location on the platform throughout the ordering process. The information extracted from each stone are dominant color, color composition, and histograms of structural features such as lines, layers, patterns, grain, and surface texture. This data is used to assign the stones into predefined categories.

See also the robotic pancake sorter. (via colossal)

Living in a thin moist layer on a small wet rock

posted by Jason Kottke   Nov 03, 2015

Here’s everything you need to know about the Earth, in a snappy 7-minute video. I am trying very hard not to watch the rest of Kurzgesagt’s videos this afternoon, but I did make time for this one on the Big Bang — key quote: “time itself becomes wibbly wobbly” — and how evolution works.

The weight of mountains

posted by Jason Kottke   Mar 06, 2014

A beautifully shot short film about mountains, how they form, how they age, and how they die.

Screaming volcanoes

posted by Jason Kottke   Jul 16, 2013

Volcanoes “scream” before they erupt. And they also have a heartbeat of sorts. Listen to these surprisingly intense sounds emitted by a volcano in Alaska before it erupted. The first recording condenses 10 minutes of audio into 10 seconds, so you can hear the pre-eruption scream:

The second recording is of 10 hours of pre-eruption mini earthquakes condensed into one minute of audio.

The pause right before the eruption is Mother Nature dropping the beat. (via @DavidGrann)

Hexagonal rocks

posted by Jason Kottke   Mar 20, 2013

This is an Icelandic waterfall called Litlanesfoss and the naturally occurring rock formation is columnar jointed basalt.

Litlanesfoss

The columns form due to stress as the lava cools. The lava contracts as it cools, forming cracks. Once the crack develops it continues to grow. The growth is perpendicular to the surface of the flow. Entablature is probably the result of cooling caused by fresh lava being covered by water. The flood basalts probably damned rivers. When the rivers returned the water seeped down the cracks in the cooling lava and caused rapid cooling from the surface downward. The division of colonnade and entablature is the result of slow cooling from the base upward and rapid cooling from the top downward.

One of the coolest things I have ever seen. Looks totally fake, like they built it for Fractal Falls in Polygon Gorge at Disneyland or something. Giants Causeway in Northern Ireland looks amazing as well. Check out several similar formations from around the world.

The colorful Danxia mountains of China

posted by Jason Kottke   Oct 18, 2012

Danxia refers to a “type of petrographic geomorphology” found in China. What that means is you get these mountains that look as though they were decorated with crayons by a five-year-old channelling Dalí.

Danxia Mountains

That shot was taken by Melinda ^..^ on Flickr…you can find dozens of her Danxia photos here. A kottke.org reader suggests that Tiny Wings creator Andreas Illiger was influenced by the Danxia landforms in developing the iconic scenery for the game.

Tiny Wings Danxia

Not a bad theory. (thx, christopher)

What if the Earth stopped spinning?

posted by Jason Kottke   Jul 27, 2010

Using computer modeling, it’s possible to take a crack at answering that question.

No spin USA

If the earth stood still, the oceans would gradually migrate toward the poles and cause land in the equatorial region to emerge. This would eventually result in a huge equatorial megacontinent and two large polar oceans.

There’s going to be a floodie floodie

posted by Jason Kottke   Dec 10, 2009

Five million years ago, a flood filled the Mediterranean Sea in only two years.

In a period ranging from a few months to two years, the scientists say that 90% of the water was transferred into the basin. “This extremely abrupt flood may have involved peak rates of sea level rise in the Mediterranean of more than 10m per day,” he and his colleagues wrote in the Nature paper.

Planning for a million years

posted by Jason Kottke   Nov 23, 2009

BLDGBLOG has a fascinating interview with geoscientist Abraham Van Luik about how to confine nuclear waste for 1,000,000 years at the Yucca Mountain nuclear waste repository in Nevada. One of the problems is keeping people away from the site in the far future:

We have looked very closely at what WIPP is doing — the Waste Isolation Pilot Plant in New Mexico. They did a study with futurists and other people-sociologists and language specialists. They decided to come up with markers in seven languages, basically like a Rosetta Stone, with the idea that there will always be someone in the world who studies ancient languages, even 10,000 years from now, someone who will be able to resurrect what the meanings of these stelae are. They will basically say, “This is not a place of honor, don’t dig here, this is not good material,” etc.

New ocean!

posted by Jason Kottke   Nov 05, 2009

A 35-mile-long rift in Ethiopia will eventually become a new ocean.

Using newly gathered seismic data from 2005, researchers reconstructed the event to show the rift tore open along its entire 35-mile length in just days. Dabbahu, a volcano at the northern end of the rift, erupted first, then magma pushed up through the middle of the rift area and began “unzipping” the rift in both directions, the researchers explained in a statement today.

We should name it Billy. (via clusterflock)

Instant walls of sand

posted by Jason Kottke   Apr 20, 2009

Magnus Larsson has proposed building an ingenious structure in the Sahara Desert: a 6,000 km-long wall of sandstone made by flushing bacillus pasteurii through loose sand. The bacteria quickly solidifies the sand, thereby providing a wall to stop the advance of the desert or even structures for people to live in.

I researched different types of construction methods involving pile systems and realised that injection piles could probably be used to get the bacteria down into the sand — a procedure that would be analogous to using an oversized 3D printer, solidifying parts of the dune as needed. The piles would be pushed through the dune surface and a first layer of bacteria spread out, solidifying an initial surface within the dune. They would then be pulled up, creating almost any conceivable (structurally sound) surface along their way, with the loose sand acting as a jig before being excavated to create the necessary voids.

This sounds more like sculpting or baking than architecture.

Obama elected by “rich loamy soils” of Cretaceous seas

posted by Jason Kottke   Nov 20, 2008

The 2008 election voting patterns in the southern United States followed the big cotton production areas in 1860 which in turn followed the shoreline of the shallow tropical seas that covered the southern part of the US 85 million years ago.

This is not a political blog. However, this is a story I couldn’t pass up: the story of how voting patterns in the 2008 election were essentially determined 85 million years ago, in the Cretaceous Period. It’s also a story about how soil science relates to political science, by way of historical chance.

Headline I’d like to see in 96 pt. type in the NY Times: Obama Elected By Rich Loamy Soils of Cretaceous Seas.

Five ways to trigger a natural disaster

posted by Jason Kottke   Jul 30, 2008

Human activities can trigger natural disasters such as earthquakes and flooding.

“Dams are the most dangerous man-made structure likely to cause quake,” says David Booth of the British Geological Survey. By artificially holding a large volume of water in one place, dams increase pressure on fractures beneath the surface of the earth. What’s more, water has a lubricating effect, making it easier for the fractures — or faults — to slip.

The sliding rocks of Racetrack Playa.

posted by Jason Kottke   Nov 30, 2007

The sliding rocks of Racetrack Playa.

These rocks can be found on the floor of the playa with long trails behind them. Somehow these rocks slide across the playa, cutting a furrow in the sediment as they move. Some of these rocks weigh several hundred pounds. That makes the question: “How do they move?” a very challenging one.

Includes some nice photos at the end. (via clusterflock)

Geological features called chevrons could be evidence

posted by Jason Kottke   Nov 16, 2006

Geological features called chevrons could be evidence of violent comet/asteroid impacts as recently as 1000 years ago. The chevrons are formed by massive tsunamis; scientists believe one such tsunami occurred in the Indian Ocean 4,800 years ago and was 600 feet high. These impact-caused tsunamis may also be responsible for the various flood myths found in world religions. (thx, matt)

Satellites measuring the earth’s gravity from orbit

posted by Jason Kottke   Aug 10, 2006

Satellites measuring the earth’s gravity from orbit detected a change in gravity from the massive earthquake that caused the tsunami in the Indian Ocean. “The gravity at the earth’s surface decreased by as much as about 0.0000015 percent, meaning that a 150-pound person would experience a weight loss of about one-25,000th of an ounce.”

BLDGBLOG posts a series of maps showing

posted by Jason Kottke   Apr 19, 2006

BLDGBLOG posts a series of maps showing how, through the movement of the earth’s tectonic plates, North America came to its present position and shape. Full set of maps here.

Update: Mike Migurski combined the maps into an awesome movie spanning 550 million years. It’s….wait for it…..the longest movie ever made!

A convergence of fault lines in Africa

posted by Jason Kottke   Mar 28, 2006

A convergence of fault lines in Africa near Ethiopia, Eritrea and Djibouti is shifting the land so much that eventually the Red Sea will flow in and create a new ocean. (thx, brian)

Is Taipei 101, the world’s tallest building, causing

posted by Jason Kottke   Dec 05, 2005

Is Taipei 101, the world’s tallest building, causing earthquakes? “The considerable stress might be transferred into the upper crust due to the extremely soft sedimentary rocks beneath the Taipei basin. Deeper down this may have reopened an old earthquake fault”. (thx, malatron)