Tuesday, March 29, 2011

Mining the Internet: ArcGIS

In this article, I want to accomplish just three things:

1) introduce you to ArcGIS, a new tool

2) update you on GeoCommunicator, an older tool that’s seen some major improvements, and

3) talk a little bit about magnets.


Late last year I sat down for lunch with Evan LaCour, one of my readers. Evan is a young man with a geography degree specializing in geographic information systems (GIS). We’ve kept in touch since ever since, mostly by email through LinkedIn.com. He sent me a quick note recently about ArcGIS Explorer. It allows people to share maps, data, and tools online. There is also a desktop version available for those who don't have high speed access.

Here is the site: http://explorer.arcgis.com/. You need Microsoft Silverlight installed, which stopped me for a second. I had to reformat a laptop once thanks to a desire to use Silverlight to stream NetFlix movies to my television. It took two days to recover from that fiasco, but I’m sure there was more pilot error involved than blame for a rogue software program. Eventually, you should see the map in Figure 1:

Figure 1. Main ArcGIS screen, ready for map overlays that you select. Remember that you can click on an image to make it bigger...

Once you reach the main map, click the "map center" link in the upper left corner. It’s not intuitive, but there is a rollover if you hold the mouse over the icon long enough. I highlighted the map center link in Figure 2:

Figure 2. The Map Center button is in the far upper left corner.

The Map Center button takes you to the “Featured Maps” page. Since there’s no telling what the site managers might choose to highlight from day to day, you’ll want to learn to search the contents to find what you’re looking for. Click the blue Search bar on the left and bring up the Search screen. Type "geology" into the box and click the [Search] button. You should get a few pages of geology-themed maps to choose from.

There are topographic maps, hazard maps, mine dangers, earthquake locations, and lots more. My current favorite is the “Community Geology Base map,” which covers North America. You can zoom into your state and watch as it dynamically loads the data at different scales. Most of us have a scroll mouse now, and this will zoom in and zoom out on the data.

For example, I’ve been gearing up for a visit to the Burnt River area of eastern Oregon. The geology here is old and complicated, with Jurassic and Cretaceous granite intrusions colored pink and labeled JKg, recent Quaternary river gravels and alluvium colored yellow and labeled Qal, and so forth. I pulled out a screen shot in Figure 3.

Figure 3. ArcGIS Geology map for the Burnt River, Oregon vicinity.

One feature that will help you is the “Identify” button up in the ribbon at the top of the page. The most common need to do this would be to learn more about the color on the map, which represents a rock type, formation, or other major unit. Click this button, shown in the snip below, and you should be able to then left-click inside the map for more information.

Sometimes you’ll get a formation name, age, and rock type. Other times, you don’t get much more than the age of the rock. There are often links to the

source map, so you can chase down detailed geology from there.

I like to use a topographic map as the base, using the “Basemap” icon in the ribbon. You can go with various satellite images as well.

ArcGIS Explorer allows people who don't have a GIS or a mapping background to create and easily make, use, or view maps. You could add you own data to existing maps to create your own custom maps. You can even code your own maps that are shared on that site and combine data from multiple other maps or servers. You could plug in your GPS, use the data in GIS or other programs and add it to the web maps. In short, there’s a lot of power here.


A friend recently asked me about the Hansen Creek quartz crystals at Snoqualmie Pass in Washington state – he wanted to see if the claim activity had changed in Township 22N Range 10E Sections 15 and 22. The best tool to figure out claims is the Bureau of Land Management’s GeoCommunicator site at http://www.geocommunicator.gov/blmMap/Map.jsp?MAP=MC.

I zoomed in to Washington state and the pass area, and brought up the usual view. The maps looked more up-to-date than I remembered, and I could see claims I knew about easier. Then I clicked on the “i” button, also known as the Identify button.

Figure 4. Geocommunicator ribbon bar, showing "Identify" button.

This caused the cursor to change shape. So I clicked in the claim area, and after some throat-clearing, the following report came up in Figure 5.

Figure 5. Claim report from using "Identify" button.

All of these listed claims are closed. But the hatching indicates there are still open claims, which verified what I remembered. I ran a Mining Claims report from the upper right with the little prospector icon. I set it for Washington State and King County, and didn’t even bother with the Township and Range setting. I got the report in Figure 6.

Figure 6. Two active claims in the Hansen Creek area.

Garden Slug and Banana Slug are the two active lode claims, and have been there forever. That meant the information in my book “Gem Trails of Washington” was still accurate, which was a relief.


On a recent outing in western Washington, we fought the urge to set up a primitive camp because of the rain. Instead, we paid for a U.S. Forest Service site at Coho Campground on Lake Wynoochee. Once we got settled and made a fire, someone pulled out one of my big, round magnets I’d recycled from a stereo speaker years ago. We tied a string on it and dragged it around, and sure enough, we soon found a bottle cap, rusty safety pin, three nails, a washer, and two screws. We also recovered enough magnetite to fill up a small eight-ounce pop bottle.

From there, the conversation went to meteorites, and for the next day, we dragged the magnet around on the various gravel bars we inspected. Sure enough, the darned thing broke on us – without recovering any heavy, rusty, or black rocks we could test for extra-terrestrial iron. We did clean up a lot of junk, however, so that was rewarding.

When I got home, I ordered up a big ringed precious-metal magnet. There are various vendors online, such as www.Magnet4less.com, www.duramag.com, www.kjMagnetics.com, and www.rare-earth-magnets.com to name just a few. These sites sell high-quality permanent magnets with ten times the strength of my old ferrite magnet, and they’re tougher, too. Hopefully they’ll arrive before my next trip and I can provide a full report.


Modern-day prospectors have great tools at their disposal, so it’s a shame not to use them. After my last column, requesting more Facebook and LinkedIn friends, I’ve received dozens of Friend requests, which has been a lot of fun. I’ve got links now to readers all over the world, and you’ve been unfailingly polite and inquisitive. I’ll try to keep sharing links and events that I discover, and I hope you’ll do the same.

[Update - since I wrote this, the GeoCommunicator site no longer provides visual claim information. I'm investigating...]