Readings: Scan the intro section in the Help portion of ArcGIS. It will be quite helpful to do this before tackling the exercise.
Some introductory thoughts: Academic/disciplinary tribes exist and they fight over territory because they are populated by humans. Historically, GIS has been in the midst of such turf battles. This is evident in the 4 -5 different descriptions of GIS in Clarke's (2001) intro to GIS text, but also in many other ways. As my one advisor used to say, "where there are 3 people there are politics". I mention it here because if you are aware of this turf battle you can avoid it - it produces few solutions to answers, and produces mainly intractable behavioral problems. Perhaps, better questions to concentrate on are as follows. Can GIS be helpful in solving a particular problem at hand. What types of problems can it solve? What types of insights can it bring to light? How can the data be best 'visualized' and/or analyzed in different circumstances? What are its limitations? What is the quality of the products produced with it? It may simply be that GIS is an integrative computer representation and/or model and/or analysis of some part of the universe with a fundamental map perspective, but that description covers a lot of ground. More simply it might be a software environment made of map layers with map elements linked to relational databases, coupled with analytic tools. One thing is clear, it is being utilized by many scientists more and more, and is a powerful tool. that being said, the old adage "garbage in - garbage out" still applies.
Map layers as key organizational structure: Complex natural system behavior is driven by multiple variables, including human factors. Therefore, when trying to understand, predict or manage the behavior of these systems one needs to integrate multiple types of information. Spatial patterns and variation in these variables/factors is fundamental, especially for geoscience and earth system science. So a computer environment where you can look at and analyze the spatial distribution of different types of information is distinctly advantageous for trying to understand complex systems, especially those with both human and physical components. In the GIS environment each layer represents a certain type of information. Very different types of information can be displayed in each layer (both of a raster and vector type). The information in each layer can be classified and displayed in different manners. New layers can be created from operations on existing layers. An example of a collection of GIS layers is seen to the right, and comes from a USGS site "USGS Studies in Long Island Sound: Geology, Contaminants, and Environmental Issues" - http://woodshole.er.usgs.gov/project-pages/longislandsound/data/GIS.htm .
What can GIS be used for? Naturally for a myriad of things. A partial list is below.
Image created in GIS environment of Mauna Loa NE rift zone recent flows. As you can see here one type of information can be 'draped' on an underlying surface - in this case the topography of island. Image source: http://hvo.wr.usgs.gov/volunteer/gis/
Above is a figure from Ryan Korth's UNO senior thesis looking at the distribution of earthquakes in the Great Plains area. Each dot is an earthquake epicenter, and the underlying map is part of the USGS Geologic Map of North America (that you will be also using in your exercise). Ryan took data from the IRIS earthquake database and added to it documents on the locations of historic earthquakes for the three state area of South Dakota, Nebraska and Kansas. He then analyzed it in GIS in a variety of ways. Here he has used one of the "toolbox" routines do to a simple cluster analysis, where the strength of a cluster shows as different shades. Clusters would be expected along active tectonic features. The two major clusters to the west in NE and KS are also areas of secondary recovery activity in oil fields and the cluster may be due to induced seismicity. However, other clusters , such as the one in the middle of the Sand Hills reflect some unknown, seismically active, feature. The clusters in SE NEbraska and down into NE Kansas are associated with the underlying, buried Keweenawan age rift, and this zone in Nebraska is known as the Humboldt fault zone.
GIS software architecture components: One way to ain insight into GIS is by what the software does. The following is a list of common components:
Key aspects of GIS packages:
Language as key: There is a lot of new language in GIS. Some of it is specific to a given software environment. Below are just a few terms as examples of how a word takes on a new specific meaning.
A quick history of ESRI GIS products:
Three levels of learning the software:
Some types of ArcGIS files: (files are identified by the .suffix.)
This software environment creates a tremendous number of files, and therefore file organization and management becomes important for projects with even a modest number of layers.
Map projections and such: A key, but often not initially obvious component of a GIS project is the map projection and coordinate system used for spatial location purposes. These can be manipulated and changed in ArcGIS. Description of map projections and related topics can be found at the USGS web site: egsc.usgs.gov/isb//pubs/MapProjections/projections.pdf .Problems can arise when you unwittingly bring together information from different projections. World Geodetic System 84 - WGS 84 - is a common projection used for latitude and longitude data.
Data now served in ArcGIS format:
Site that shows animation of oil/gas discovery through time, animation of GIS data - http://pubs.usgs.gov/dds/dds-069/dds-069-q/graphic/video/DDS69-QVideo.avi
Copyright by Harmon D. Maher Jr.. This material may be used for non-profit educational purposes if proper attribution is given. Otherwise please contact Harmon D. Maher Jr.