The cache is not at the posted coordinates!
Introduction
A geographic information system (GIS) is a computer system for capturing, storing, checking, and displaying data related to positions on Earth’s surface. GIS is the bedrock of many web applications we use on a day to day basis, including maps, navigation systems, and of course this Geocaching website.
This tutorial will introduce you to the MarinMap application, which hosts all kinds of publically available data on the infrastructure and natural geography of Marin County. Most other counties also provide GIS data in a similar way. Complete the challenge at the end of this tutorial to obtain the final coordinates to the cache. Begin by opening the app using the link below (note that this may be difficult to use on your mobile phone):
https://www.marinmap.org/Html5Viewer/Index.html?viewer=smmdataviewer
Navigating MarinMap
1. Zoom into the city of Novato in the map window. You will notice that some map layers are shown by default, including city boundaties, districts, and parks.
2. Suppose you're looking for interesting geological features to highlight for a new EarthCache. Go to the panel on the left and select the box next to "Hazards and Geology." Then, use the plus sign to expand this category.
3. Scroll down to "Geology" and select it. This will add data on geological freatures to your map. Click on the list icon next to the checkbox to bring up a key.
Queries
4. That's a lot of data to look at! Suppose you want the map to show only a specific kind of rock. Click on the "Tasks" section of the toolbar near the very top of the page. Then, click on the "Query" tool below.
5. In the sidebar, set the data source to "Geology" and the map area to "Current Extent." This will only search within the area of the map that is currently visible on your screen.
6. Use the three fields below to spell out "PType = sp" and click "Search." This will highlight only the areas in Novato containing serpantine, California's state rock.
Finding the geocache
Pictured below is the spot where I hid the cache. Use what you've learned to find the location of the mile post, located somewhere in Novato. Good luck!
You can validate your puzzle solution with
certitude.