And by getting high, of course I mean (a) going to the Griffith Observatory high in the Hollywood Hills, and (b) huffing hydrocarbon fumes at the Rancho La Brea Tar Pits. What else would I mean?

So first, some words of advice for anyone going to the Griffith Observatory.

  1. Get there early. At least 30 minutes before it opens. There is limited parking and you don’t want to have to parallel park on a steep, winding, two lane road next to a thousand foot drop, do you? (Ok, maybe it’s not a thousand feet, but it’s high enough to hurt.)
  2. If you’re using a GPS, don’t count on it to get you to the observatory. Mine produced a couple big gaps in the route, and I didn’t find any teleporters, so I’m not sure how it expected me to get there. Also, don’t fall for the idea that if it just gets you to Griffith Park, you’ll surely see some signs pointing you to the observatory. The kindly Los Angeles city planners apparently didn’t think that would be a good idea. I spent nearly an hour driving through Griffith Park, with no signs to suggest the Observatory even existed. Tell your GPS to take you to the Greek Theatre. By the time you get there, you’ll have seen enough signs to know that the Observatory is just a little further along the same road.
  3. See the planetarium show! It’s worth the extra $7.

So, here we are looking at the famous façade of the Observatory. And you can see what a lovely, clear day it was.

I even found a hummingbird flitting about the base of the astronomers’ monument.

You can take advantage of the fact that you got there early (refer to #1 above) to take in the breathtaking view of LA and its smog.

And the Hollywood sign.

Once you’re inside, there are the typical kinds of exhibits you’d expect to find at an observatory: what makes seasons and eclipses, how tides work (maybe Bill O’Reilly should check that one carefully), how Galileo built his telescope and discovered the four biggest moons of Jupiter, etc.

Since I was there during the day, the only thing for the observatory to observe, really, is the Sun. And they do have a telescope pointed at it. And you can watch it live without risk of freaking out your retinas. It wasn’t doing anything interesting while I was there, except, you know, fusing 600 million tons of hydrogen per second into helium. But no sunspots or anything cool like that.

Get it? Cool? Because sunspots are 1500 degrees cooler than the surrounding surface? Never mind.

Anywho, my favorite part was, probably not surprisingly, the meteorites. Because they’re rocks. Rocks from space. And because analyzing them has given us a lot of insight into the formation of the solar system.

They don’t have nearly the meteorite collection that the Smithsonian has, but they have a few. Of the three basic types of meteorites, I’ve got to pick the iron meteorites as my favorites.

Don’t you love that Widmanstätten pattern? Touching one of these is as close as we’ll probably ever get to touching the core of the Earth. Except much, much cooler. Temperature-wise, anyway. These meteorites are thought to come from the cores of asteroids. Asteroids formed pretty much the same way the inner, rocky planets did. They just didn’t progress as far because the gravity of Jupiter kept them from sticking together.

As the spinning cloud of gas and dust that came from a supernova explosion and subsequently made the solar system started to coalesce, the heat of gravitational energy melted the rock and metal, causing them to separate out based on density. The metals (mainly iron and nickel) sank to the middle and the silicate rock surrounded it, forming a core, a mantle, and a crust. Just like on Earth. But since asteroids are so much smaller than planets, they cooled much faster.

Meteorites that come from the core-mantle boundary are called stony-iron meteorites:

I have to admit, I like these too. Because they’re filled with my birthstone! Just like on Earth, the mineral olivine (the gem quality versions of which are called peridot, the August birthstone) is a silicate that forms in the mantle. On Earth it’s commonly associated with silica-poor igneous rocks like basalt.

Lastly, there are the stony meteorites.

There are two types of stony meteorites: chondrites and achondrites. Chondrites have chondrules, unsurprisingly, and, because they have not been melted, are thought to be the original material from which the solar system was formed. They contain tiny bits of metal, silicates, and olivine. That’s what the chondrules are. But you need a microscope to see them.

Achondrites do not have chondrules and have thus undergone melting. They look a lot like igneous rocks from Earth, suggesting that they come from the crust or upper mantle of fully formed asteroids.

They also have meteorites from the Moon and Mars which you can touch! So that was kind of awesome.

A couple other cool things live in the bowels of the Observatory. First, there is the largest astrophotograph ever produced, which covers one entire wall of the lower level. My picture of it came out terribly, so I won’t inflict it on you, but believe me when I say it’s ginormous. Every little speck of light is a galaxy. And the span of sky it looks at would be covered by your finger held at arm’s length.

Second, there’s a seismograph.

The Earth was surprisingly quiet while I was there.

And now on to the tar pits.

I’ve been to the tar pits at least a couple times in my life, and there are two things I remember about them: the smell; and the steep hill around the museum that was fun to roll down as a kid. Neither has changed in the last 25+ years. And kids were still rolling down the hill when I was there.

There’s a common perception (and I suffered from it too) that the tar pits got their impressive cache of fossils because animals unwittingly walked into deep pools of tar and quickly sank as if in quicksand. At least that’s how the Simpsons portrayed it. And that’s where I learn all my science. The museum tries to dispel this idea, although their own little diorama next to a giant lake of tar probably doesn’t help their efforts.

The tar pits (more accurately, asphalt seeps) formed because the LA basin was, during the Mesozoic era (250-65 million years ago), at the bottom of the ocean. During this time, it collected lots and lots of organic marine sediment. Eventually, tectonics started happening, and the area would be alternately uplifted (collecting continental sediment) and eroded back down (collecting marine sediment).

Eventually a basin formed that got cut off from the ocean and started filling up with sediment from the mountains (like the Santa Monica mountains) that started uplifting around it (more tectonics!). All of this debris on top of that old organic marine sediment greatly increased the temperature and pressure and converted it to petroleum.

Asphalt is just petroleum that has lost most of its volatile compounds and can be quite sticky when warm. As more and more faulting and uplift and compression started going on in the area, the asphalt started flowing to areas of the rocks with more breathing room. And eventually, that meant up to the surface, like this baby tar pit that’s trying to form. Awww, how cute.

Over a period of 30,000 years, individuals representing 58 species of mammals, 138 species of birds, 24 species of reptiles, and 6 species of amphibians, not to mention all the mollusks and arthropods and plants, became entrapped in the asphalt. About one third of the species thought to have lived in Pleistocene era North America have been found at the tar pits.

So how did it happen? It takes only two to three inches of asphalt for a large mammal to become immobilized. Once stuck there, it would either fall prey to predators or die of starvation and thirst. In fact, the fossils of predators found at the tar pits vastly outnumber the herbivores, a ratio that does not exist among the living. It seems that the sight or sound of a mammoth or horse struggling in the asphalt was too much to resist for a sabertooth cat or a dire wolf, with the result that the predators fell victim to the asphalt as well.

So how common an occurrence was this? Based on the time period during which the fossils became entrapped, all of the over 1 million fossils can be accounted for by just one entrapped herbivore attracting a handful of carnivores per decade. So they didn’t even have the chance to learn from each others’ fails.

People lived in the area eventually, of course, but only one fossilized human has been found in the tar pits. She is called, appropriately enough, La Brea woman. Nobody knows how she died, but some artifacts found with her are suggestive of grave goods. What is known, however, is that her people collected the asphalt and used it as glue and caulking, and traded it throughout Southern California.

So, on to the fossils. The most common fossil found at the tar pits is that of the dire wolf. They were similar to living gray wolves but with shorter legs, so they probably did not run as fast. It is thought that they hunted like hyenas do, taking turns chasing their prey rather than stalking and pouncing.

There have been so many dire wolf skeletons found in the tar pits that they have a wall of dire wolf skulls in the museum.

The second most common fossil is the sabertoothed cat. I think the best thing about these guys is their scientific name: Smilodon fatalis. Don’t you just love that? And it seems highly appropriate.

These things could roar like a lion and appear to have lived as social animals, given the number of healed fractures and other severe injuries seen in the fossils. Someone was obviously helping the lame ones find food while they recovered.

Given the importance of their sabers, it’s probably no surprise that they didn’t lose their baby sabers until their adult sabers had fully erupted.

I gotta say, I’m kind of glad these things are extinct.

Another carnivore whose extinction I celebrate is the giant short-faced bear. “Giant” because these things were bigger than grizzlies! And like grizzlies, they seemed willing to eat just about anything.

Ok, enough of the scary predators. How about….camels? Yes, camels used to live in North America. In fact, camels evolved in North America and spread to Asia, then mysteriously died out here.

Horses too. There were horses native to North America, which then became extinct. Horses were then reintroduced by the Spanish. And wild horses survive in the US just fine today, so it doesn’t seem to have been the climate that pushed them to extinction.

Some of the fossil horses still have food stuck in their teeth! So we know what kinds of things they were eating.

Sloths are kind of interesting, not least because they had bones in their skin called dermal ossicles. So take that, sabertooth cats! This is a Harlan’s ground sloth.

One thing that I found fascinating, probably because of my microbiology background, was the number of bacterial species have been found in the deposits. These have been discovered through molecular techniques, which shouldn’t come as a surprise. Genera include: Bacillus, Pseudomonas, Citrobacter, Bacteroides, and Microbacterium. Some of those should be familiar to anyone who has studied human bacterial diseases.

There are several other interesting fossils, pictures of which you can find on my Flickr page.

One of the things that is fun to do while visiting the tar pits is to watch excavations live. They only do this for two months per year because of funding. They usually do it during the summer because (a) that’s when they get the most visitors and (b) that’s when the asphalt is least viscous, making it easier to work with. However, they’ve suspending work on the deposit they’ve been excavating since 1969, pit 91.

Next door to the tar pits is the LA County Museum of Art. While digging out the foundation for a new parking structure, they found a lot of fossils. Rather than delay construction to excavate, they removed the fossils en bloc and moved them to the tar pit grounds in 23 huge crates. Hence “Project 23”.

So, about that smell. Turns out methane and hydrogen sulfide are still bubbling up out of the asphalt. I wish my camera could capture the aroma so you could share in it too.

Incidentally, during the week that I visited these places, I was camping at Malibu Creek State Park. If you want to know why that sucked, let me know. One thing that didn’t suck was getting a daily visit from this guy (or at least one that looked just like him):

I also interrupted a family breakfast while driving out one morning:

And then there was this nearby:

Look at how much uplift that thing went through to make those formerly horizontal layers now nearly vertical! This was in the Santa Monica mountains, by the way. So that’s the kind of uplift that contributed to forming the tar pits.

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