Friday Rocks: K/T Boundary

My Friday Rocks photo shows the K/T boundary, aka the Cretaceous/Tertiary Boundary. I took this photograph in August 2011, when I was out in the field with the Dig School, a wonderful education program co-founded by Burke Museum paleontologists Greg Wilson and Lauren DeBey. We were about 16 miles north of Jordan, Montana. The site is known to paleontologists as Lerbekmo Hill, after geologist Jack Lerbekmo. One of the highlights of the spot is that I could place my hand on the iridium anomaly layer, the famous bed of material that helped geologists understand what happened to the dinosaurs, and many others, at the end of the Cretaceous. In addition, about ten miles away is the location where Barnum Brown found the first specimen of Tyrannosaurus rex. It’s certainly one of the niftiest spots for any geogeek to visit.

Here is another view of the location showing the different layers.

K/T Boundary

Friday Rocks: Photo in the Field

I thought I’d try something different this week, at least different for me, and post a shot from the field. This spot illustrates one of the most famous moments of time in geology. What makes this location most compelling is that it is near where some of the world’s most famous extinct beasts were found. It’s just a hundred yards or so off of dirt road. Any guesses where the shot was taken and what it shows?

Where is it? What is it?

Where is it? What is it?

Building Stone Tours

For several years I have given tours of Seattle’s building stones. Now, I am trying something new. I am offering the tours through Groupon/Sidetours. Sidetours advertises itself as “Do Something Memorable.” They offer tours with experts in a variety of locations. Mine is one of many in Seattle. Here’s more information on my walks.

The tour is available on the following dates and times.

September 13 – 10AM to Noon
October 11 - 10AM to Noon
October 17 - 10AM to Noon
October 18 - 10AM to Noon

Serendipitous Marble Vein - Three on the Third

I recently learned about this serendipitous vein in a marble slab in a downtown Seattle building. I like to think that the worker who placed this slab did it knowingly. It certainly looks that way to me. The marble is Alaskan marble, though it is not in the Smith Tower.

Number Three on the Third Floor

Close up of the number Three

Walk Added

The Seattle Audubon Society has added a second time for the class/walk on building stone that I am leading on August 2. The first walk, at 10am filled. The second walk will be at 1pm and last until 3pm. The walk covers about 1.5 miles as we explore the building stone of downtown Seattle. For more information go to the classes page on the Society’s web site.

Some of the building stone we will see.

Cairns in Spokane

As many people know, cairns aren’t only found on the trail. Turns out that people near downtown Spokane, Washington, are making them. And the cairns are more than simple stacks of stone. Brick, asphalt, concrete, and stone are turning up in the cairns.

According to an article in the Spokesman-Review, the cairns began to appear a few months ago. At this point, the cairn builders are remaining anonymous. The area is part of a new development in the city called Kendall Yards and the cairns are in a recently graded section. Cat Carrell, who is helping to develop the area with Greenstone Homes told a TV reporter that ”as far as I know the cairns are going to stay until something else happens on that lot.”

Save Our Cairns

Karen Daubert, Executive Director of Washington Trails Association, recently sent me information about an initiative about cairns in the northeast. The goal is to protect cairns on mountains, as well as to protect the environment where the cairns are built. According to longtime Appalachian Mountain Club volunteer Pete Lane, “Cairns in our area are being damaged and as alpine stewards, we need lots of help to get the word out about leaving them as they are.” As Lane and others involved in the working group note, cairns have long been an essential element of safe hiking in northeast but in recent years these wonderful little piles of rocks have not fared well. The initiative is organized by Leave No Trace.

People not only are destroying cairns but also building too many of them, which can lead people astray and damage the environment, when cairns builders pry up rocks in the fragile alpine ecosystems for cairns. This situation has particularly been bad in national parks and along the Appalachian trail, where people regularly damage cairns despite the best efforts of rangers and volunteers.

The working group has published a set of guidelines for minimizing impact on cairns. Here they are. (From the web site.)

1. Do not build unauthorized cairns. When visitors create unauthorized routes or cairns they often greatly expand trampling impacts and misdirect visitors from established routes to more fragile or dangerous areas. This is especially important in the winter when trails are hidden by snow. Thus, visitor-created or “bootleg” cairns can be very misleading to hikers and should not be built.
2. Do not tamper with cairns. Authorized cairns are designed and built for specific purposes. Tampering with or altering cairns minimizes their route marking effectiveness. Leave all cairns as they are found.
3. Do not add stones to existing cairns. Cairns are designed to be free draining.  Adding stones to cairns chinks the crevices, allowing snow to accumulate. Snow turns to ice, and the subsequent freeze-thaw cycle can reduce the cairn to a rock pile.
4. Do not move rocks. Extracting and moving rocks make mountain soils more prone to erosion in an environment where new soil creation requires thousands of years. It also disturbs adjacent fragile alpine vegetation.
5. Stay on trails. Protect fragile mountain vegetation by following cairns or paint blazes in order to stay on designated trails.

All good advice, which is applicable to anywhere you find cairns, whether in the northeast, the Sierras, or the American southwest. With hiking season on us, this another good lesson in how to lessen our impact on the ecosystems we love to explore.


Singing Stones

Summer solstice often elicits strange stories about Stonehenge. Now we learn that the builders of the ancient site may have chosen their building material for the simple reason that they were musical, with they meaning both the rocks and the builders. In a recently published article in Time and Mind: The Journal of Archaeology, Consciousness, and Culture, researchers Paul Devereux and Jon Wozencroft propose that the bluestones used in Stonehenge were transported more than 125 miles for their acoustical quality. The bluestones, a collective term for dolerites, rhyolites, and tuffs, come from the southwest corner of Wales. The area is known as Mynydd Presell and is famous for the rocky outcrops known as carns.

The study grew out of Devereux and Wozencroft’s work looking at how our senses might have influenced our relationship to landscape. What they found is a visual connection between the natural outcrops and numerous man-made structures, particularly dolmens. When they turned to sound, they discovered that the Welsh bluestone was a “noteworthy soundscape” filled with many ringing rocks. They propose that it is “highly improbable” that the Neolithic stone masons were “unaware of the echoes and the sonic characteristics of many of the rocks around them.” Unfortunately, when they tried to test the bluestones used at Stonehenge they met with little success, primarily because the stones were set in the ground and concrete, which tended to dampen the sounds. Despite this situation, they are hopeful that their work will encourage others to further the study of lithophones, or rocks used deliberately for their sound qualities. For more information, you can read an article in the New York Times.

I was very excited to read this study as I have long been intrigued by the sounds of stone. I first encountered this phenomenon in southern Utah with the Navajo Sandstone. Walking through the petrified dune field of the Navajo, I periodically came across gray rocks that rang when I stepped on or kicked one. The white or red layers of the Navajo lacked this quality. I eventually found out that the gray layers were ancient playa deposits, preserved as limestone lenses within the sandstone. Like the bluestone, the limestone was very dense. And since the rock often weathers out into boulders, they were in a perfect space to produce sound with plenty of air around them for resonance.

Another time I noticed ringing rocks was at the Getty Museum in Los Angeles. The complex is covered in thousands of three-inch thick panels of travertine, which comes from quarries in Tivoli, about 20 miles from Rome. Best known for its use in the Colosseum, the 80,000-year-old rock is a type of limestone that forms in hot springs. I discovered the sound qualities of the Getty travertine during a visit while I was working on my book Stories in Stone. About half way through my tour, I rapped one of the panels and was startled by its tone. The travertine is very dense but these panels also ring because of how they are mounted. Each panel is bolted about three-eighths of an inch away from each surrounding panel and from its concrete backing. The builders did this so the panels could move when the next earthquake hits. As with the Navajo, the air space allows the stone to resonate and because every panel at the Getty is different, each one produces a different sound. Pretty cool, I think.

Whether the ancient builders of Stonehenge actually chose the bluestones for their musical qualities is not terribly important or life changing. What is important though is that the researchers took the time to observe and to consider the bigger picture of our relationship to the world around us. When we do this, we may not hear songs, but I suspect we will have richer lives.

What's Under Seattle

As the state museum of Washington, the Burke Museum is the official repository for many of the wonderful natural and cultural history cultural that have been found or produced in the state. This includes items discovered during the many engineering projects that have shaped Seattle. To help familiarize people with some of the objects, the museum is hosting an event tonight, Thursday, February 6, as part of the city’s First Thursday events. This is the day that many museums in Seattle are free to visit.

The Burke’s event is titled, What’s Under Seattle. My colleague at the museum, Archaeology Collections Manager Laura Phillips, and I will be leading the event. Our plan is to discuss some of the landscape changes in Seattle and to share some of the objects that have been excavated during the excavations. We will also address that giant machine under the city, Bertha, and consider some of the issues that ail her. Hope you can attend.

We will be speaking at 6pm in the museum on the University of Washington campus.

Golly ned, that's a big Cairn

My pal Dave Tucker sent me this great shot of a new cairn. Here’s what he told me.

“The City of Bellingham recently completed a new roundabout at the intersection of S. State, Wharf, Forest, and Boulevard. They placed a large cairn in the center [lit at night]. The bottom two, and uppermost, rocks are dunite, presumably from the Twin Sisters. The second to top is serpentinite. The stones are balanced and are about 12′ feet tall- somewhat foreshortened
in this photo.”

Way to go Bellingham.


One Big Cairn