Geograph CA

What if you could hold all of California in the palm of your hand?

Geograph CA is the first GIS (geographic information system) for the iPhone.

The current version is 1.2. It contains a large number of upgrades, with new features (bookmarks in particular), two new built-in layers, and a cornucopia of additional downloadable layers: 24 as of last count.

Geology of California
Unlike Google Maps, Geograph CA is completely self-contained, which means that it is always available, even without any cellular or wireless coverage. It can be used in the field, in the middle of nowhere.
Terrain, faults and bathymetry of the San Francisco bay area
Geograph CA contains a selection of geographical information in its internal database. It can display this information in 32 different built-in layers (with many more available for download). Each layer can be individually shown or hidden, moved up or down, and made more or less transparent. This allows an almost infinite number of possible displays.
Geology, faults, roads, urban areas and USGS quadrants around Tahoe

Each feature of most layers has additional information which can be displayed by tapping the feature. This brings up a list of all the data in all the displayed layers at that point.

The user can then select the desired layer and get all the available information. For instance, tapping an area of the Geology layer brings up the following screen:

For a portable application, Geograph CA contains a surprising amount of information, enabling you to zoom all the way in to city-level details.
Geology, hydrology, roads and streets, railroads, and old mines of Sacramento
With Geograph CA, you can finally access data that is relevant to you without needing access to a computer or a network. For instance, the township and range information has proven very popular with professional users:
Urban areas, cities, earthquakes, mines and township&range around San Diego

Geograph CA can also generate high-resolution maps that you can download to your computer. The following shows the terrain of the state with the topography, counties and public lands superimposed (difficult to believe it was actually generated on an iPhone, isn't it?):