Wednesday, November 25, 2009

Flatirons ≠ pyramids, but they're still cool

I've noticed a few stories recently about Sam Osmanagich, a Bosnian archaeology enthusiast who claims to have discovered several 12,000-year-old 'pyramids' in the Balkans. The whole 'pyramid' saga mainly concerns a case of mistaken identity - the pyramids are just hills - and Indiana-Jones-style archaeology (by which I mean not very methodical, scientific or objective) on Osmanagich's part, and you can read more about it at the links below:

National Geographic:
Pyramid in Bosnia - Huge Hoax or Colossal Find?

Smithsonian Magazine: The Mystery of Bosnia's Ancient Pyramids

They're really not hoaxes or mysteries, though - just badly misidentified. I minored in archaeology in college, and it really makes me cringe to see something so pseudo-scientific be accepted by so many people, even becoming a point of national pride in Bosnia. Archaeology has become a very scientific process, and properly-conducted archaeological digs are just as methodical as anything we do as geologists. Digging holes in a hillside, finding layered sandstones and conglomerates and then declaring that they're poured concrete mostly because they look like concrete is really crappy science. (There are also a lot of archaeologists who are unhappy about the whole situation because the 'pyramid' digs could potentially destroy a lot of genuine archaeological sites, which that area of the Balkans apparently has in abundance.)

Anyway, the situation is a great big mess. But what I found really interesting in the Smithsonian article was the (much more plausible) geologic explanation for the pyramids. Here's what the article says:
Visoko lies near the southern end of a valley that runs from Sarajevo to Zenica. The valley has been quarried for centuries and its geological history is well understood. It was formed some ten million years ago as the mountains of Central Bosnia were pushing skyward and was soon flooded, forming a lake 40 miles long. As the mountains continued to rise over the next few million years, sediments washed into the lake and settled on the bottom in layers. If you dig in the valley today, you can expect to find alternating layers of various thickness, from gossamer-thin clay sediments (deposited in quiet times) to plates of sandstones or thick layers of conglomerates (sedimentary rocks deposited when raging rivers dumped heavy debris into the lake). Subsequent tectonic activity buckled sections of lakebed, creating angular hills, and shattered rock layers, leaving fractured plates of sandstone and chunky blocks of conglomerate. 
In early 2006 Osmanagich asked a team of geologists from the nearby University of Tuzla to analyze core samples at Visocica. They found that his pyramid was composed of the same matter as other mountains in the area: alternating layers of conglomerate, clay and sandstone.
Nonetheless, Osmanagich put scores of laborers to work digging on the hills. It was just as the geologists had predicted: the excavations revealed layers of fractured conglomerate at Visocica, while those at Pljesevica uncovered cracked sandstone plates separated by layers of silt and clay. "What he's found isn't even unusual or spectacular from the geological point of view," says geologist Robert Schoch of Boston University, who spent ten days at Visoko that summer. "It's completely straightforward and mundane." 

"The landform [Osmanagich] is calling a pyramid is actually quite common," agrees Paul Heinrich, an archaeological geologist at Louisiana State University. "They're called ‘flatirons' in the United States and you see a lot of them out West." He adds that there are "hundreds around the world," including the "Russian Twin Pyramids" in Vladivostok. [From pages 2-3 of the article]
Well, if you're trying to draw attention to the fact that someone's mistaking a geological formation for a man-made structure, I guess saying it isn't "unusual or spectacular from the geological point of view" is a good way to do it. But I think that flatirons are still pretty neat, even if they're made out of conglomerate, which as a volcanologist I will have to admit is not on my 'most exciting rock' list.

I've seen a few good examples of flatirons in my time out West, and I'm always impressed by the forces it took to move all that rock around. Here are some novaculite flatirons from the Big Bend, Texas region:

A great Michael Collier photo of the flatirons at Waterpocket Fold in Utah, which is part of Capitol Reef National Park:

Copyright (C) Michael Collier; hosted on the AGI Earth Science World Image Bank

(Michael Collier is an amazing photographer and a great person; I was lucky enough to meet him while I was working at AGI. I dare you not to buy a book of his photos once you've seen a few.)

And probably the most famous US flatirons, the Flatiron range just outside of Boulder, Colorado:

From Wikipedia

It's not hard to see how one of these things could get covered over with soil and vegetation and look like it was man-made. But pure observation that isn't backed up by data will give you bad results every time, and flat, triangular rock formations do not a pyramid make. It's really too bad that so many people in Bosnia are getting excited about their flatirons because they think they're remnants of an ancient civilization, and not because they're a neat geological formation that tells us about the landscape evolution of that part of the Balkans. But we can't all be geologists, I guess...

Sunday, November 15, 2009

Little Rock City

Long time, no writing! I hate dropping the ball, but schoolwork has to come first. Anyway, I spent part of this weekend exploring the geology of Western New York - specifically, south of Buffalo in Cattaraugus County.

Cattaraugus County moves away from the carbonate sequences that you see around Buffalo and into Late Devonian sandstones and shales. On the map to the left, they're shown in a sort of pistachio green, while the limestones that I live on are in dark green. (You can find a copy of this map on the UB Library's map collection website - the resolution isn't great, but it's a pretty general map to begin with.)

The weekend was a combination geology and beer-and-wine-tasting trip, but Saturday was a lovely day for hiking, so we went for a visit to Rock City State Forest (roughly near the red arrow on the map). Cattaraugus County has a number of "rock cities" - places where the Salamanca conglomerate caps hills and breaks up into large blocks along joints. According to a K/H Geology Field Guide series book on Upstate New York, "where the rock cites occur, a conglomerate ledge forms a level, ribbon-like outcrop that follows the contour of the hill for a way and then seems to just fade out."

The rock cities are really fun, and look to be prime bouldering locations; the cracks between the blocks are anywhere from inches to feet wide, so there are lots of alleys and cracks to explore.

The conglomerate is really cool; it has some beautiful cross-bedding, normal and reverse grading sequences, and imbrication in the flat pebbles that make up the largest clasts. The pebbles are mostly white quartz or quartzite, but every so often there are little bits of shale.

I'm too out of practice to be bouldering without a spotter and the right shoes, but the crack climbing was just fine for some of the folks on the trip...

The conglomerate retains water very well - I guess you could consider the blocks "perched aquifers". There are little dripping springs all over the sides of the blocks, and the water tends to pool at the bases. It makes for muddy hiking, but somebody went to the trouble of putting down wooden walkways in some spots.

Luckily, it was a nice day for hiking; it's all too easy to get so caught up in the research part of geology that you forget to go out into the field. (The crazy weather up here right now also helped; we should probably be getting snow at this point, but it was warm enough yesterday to go outside in short sleeves! I'm betting this means we're going to get dumped on this winter.)

I'd recommend a visit to anyone who's in the WNY area; this is a small but probably underappreciated park that many people would probably overlook in favor of the larger parks (or the ski areas, which I'm sure are lovely when they have some snow...)