Sunday, July 27, 2008

Off to the Field (and a Poll)!

As of tomorrow, I'm off to the field again for another two weeks or so. For your entertainment in my absence, I've opened up a poll until my return. My cynical side wanted to ask, "Which of these is the most overrated tool in paleontology?" But, I'm [usually] nicer than that (but I won't stop you from electing overrated technologies in the comments!).

See you in a few weeks.

Saturday, July 26, 2008

GPS Essentials

And we continue on with fieldwork-related posts. . .This one will probably be old hat for some of the more experienced readers out there, but I figure it doesn't hurt to lay it out for those who are curious, or those who are perhaps new to the fold. I'm talking about taking GPS coordinates!

In my last post, I discussed the importance of taking the right kinds of field photographs for documentation. A second important facet of good field documentation is GPS coordinates. Just like with photos, not all GPS coordinates are created equal.

When taking coordinates, whether they're for your own records or in order to pass them on to a colleague, context is everything. When I take a GPS coordinate in the field, I note several things:

-Coordinate system. What system are you using? Lat/long? WGS coordinates? It's self-explanatory, but at least be aware of the coordinate notation.

-Time. I always write down the time of the GPS reading. I suspect that time doesn't matter horribly in most cases, but I like to have it in the field notes "just in case."

-Accuracy. GPS units will often give you a readout of the estimated accuracy of your current reading (usually between 3 and 5 m, on the best of days, for my little Garmin). I always write this down; it's especially important to know if your coordinates might be drastically off (due to weather, topography, trees, etc.).

-Machinery. What GPS machine are using to take the readings? This is useful for real GPS geeks, who may want to know the type of firmware, software, conversion algorithms, etc.

-Datum. This is really, really critical, and a piece of information that is often neglected. NAD27? WGS84? It's all cryptic letters and numbers, but noting the datum is crucial for a person to be able to relocate your site or map it properly. Each of these datums are based on a different ellipsoid model for the surface of the earth. There isn't space to talk about the logic and meaning behind the different systems (see a decent review here), but suffice it to say that the difference between coordinates in two different datums may be tens of meters. Believe me, it's frustrating to get a set of coordinates without knowing the datum - it can be nearly as bad as not having any coordinates at all!

Thursday, July 24, 2008

Taking Good Locality Photographs

I'm back from the field for just a week, and all of that fieldwork has put me in the mood for. . .a post about fieldwork!

For those of you field paleontologists, you know what I'm talking about. Someone out hiking or prospecting saw some really cool bones sticking out of the rock. They didn't have a GPS. . .but they did have a digital camera. So, they shoot a photo of their groundbreaking discovery and proudly email it to you with a scan of a marked-up topo map. You open the email with trembling fingers, and this is what you see:

It's a pretty good photograph. . .there are pens for scale, clearly indicating the fossils that were found. Lighting is good, and resolution is excellent. But for purposes of relocating the site? Useless!

What's missing? Context, context, context! A closeup of the rock or the eroding bones is interesting, but it doesn't tell you a thing about what side of the ravine the bones were found on, how high up, or anything else. A friend and I once were sent out to relocate some dinosaur bones found by an amateur paleontologist. He had emailed a GPS point and a close-up photo of the bones similar to what I've pictured above (all good things to do!). But. . .we spent a good solid two hours trying to relocate the fossils - and never succeeded. The GPS point (assuming we were even given the right datum, or hadn't miscopied the coordinates - that's a topic for another post!) was in the base of a wash, and the photo (even though uselessly close-up) indicated the specimen was on one side or the other of the wash. The photo showed a nice hadrosaur rib, but no larger context.

Here's an example of a better field photograph. Note the fact that the photo shows the overall context of the site - crucial for relocating the correct horizon later, or when compensating for a bad GPS coordinate. If you could read the field notebook of the character who is providing the scale in this picture, you'd see that he is writing down: 1) date and time of the photograph; 2) general direction that the camera is pointing; 3) location of the fossils relative to a landmark in the photo such as a backpack or mound of rock; 4) file number of the digital photo on the camera; and all sorts of other useful informational bits. I've learned from bitter experience that these data (and then some) are what makes the difference between a useful piece of the scientific record and a pretty snapshot. The close-ups are still necessary as field documentation, but they're often secondary in importance to the broader pictures.

So the lesson here? Take good field photographs with lots of visual context - and record the important data that will be necessary for complete recall later (never trust your memory).

Friday, July 4, 2008


I'm off to the field this evening, and will return in a little over two weeks. Not that any readers of this blog aren't used to the occasional unexplained hiatus. . .

Cool Tools for Google Earth

Google Earth by itself can be a useful tool for the field paleontologist, as outlined in my previous post. Yet, some aspects of paleontological field mapping aren't supported "out of the box" within this software. For instance, many field localities are in the "Township and Range" format of the Public Land Survey System. That's the "NW1/4 of the SW 1/4, Sec. 21, T14N, R21E" style of plotting things - pretty much anyone who's done paleontology in the United States knows what I'm talking about (and how miserable it can be as a method of mapping and relocating things, versus a high-precision GPS coordinate!). Unfortunately, the default settings in Google Earth can't do anything to help on this. One or two handy plug-ins can save the day, though!

Township and Range Coverage
The Earth Point website has a KML file that provides township and range data for most of the western United States, and a handful of more easterly states. To access this, click here. For the field areas I've frequented, I've found the data to be quite accurate and easy to use. As you progressively zoom in, you can get right down to the section (and then click to get the full legal description). This is an extremely handy tool, and I strongly recommend it for any paleontologist utilizing Google Earth! Another must-have is the Township and Range Decoder. Enter a legal land description, and get it converted into Lat-Long format - or the reverse! So, so, so much easier than trying to fudge something on a topo map.

Topographic Map Coverage
I haven't used this feature as much, but did uncover two potentially handy tools. Map Finder allows you to quickly and easily find 24K topo maps within the U.S.A. - and download them for free as a TIFF file. The whole setup seemed to work pretty well for me. The Google Earth Blog details another cool plug-in, which is supposed to put the map right into Google Earth. I haven't tried it yet, but certainly will at the soonest opportunity (after I get back from the field!).

Even if it ain't open source, Google Earth has become a standard tool in my digital paleontology arsenal. It has saved me oodles of time and money, both in the field and back at the lab. If you're a field paleontologist - check it out!