Philosophy of science, and maps as important scientific tools.

What activities characterize science?

Journal writing exercise: Can your dog do science? A dog can follow a scent trail. The dog collects information with his nose. The various scents have to be classified at least into two categories, quarry and not quarry. Their behavior, e.g. following the more recent trail, suggests they can make decisions based on the input. With barks the dog can convey information to other dogs and humans. The dogs can learn from their experience. How, fundamentally, is what a dog does when following a scent different from science conducted by humans?

Some useful concepts in considering science:

• multiple working hypotheses.
• falsification.
• the nature of probabilistic statements.

Science is a human activity, and that context is especially important for this linked course. What is shared by a scientific community? Kuhn's suggestion as to four critical components are:

• exemplars: an explanation and the data it explains, training modules for the initiates.
• metaphysics: e.g. historical continuity of basic physical laws.
• language: e.g. statistics.
• values: e.g. honesty, truth is of paramount importance, love of problem solving.

A flow diagram for the scientific method of development of exemplars.

What do you do if you don't like the answer, or explanation, or model that results from a scientific investigation?

Data is the lifeblood of science. Data has different value in different contexts. It is the data-question pairing that is crucial, that can produce answers.

Types of symbolic data:

• nominal (e.g. mineral types, birth place nationality) - very important in human geography.
• ordinal (rank order but not scaled, fairly uncommon in geoscience, the Mercalli scale for earthquakes is close to one.)
• scalar (e.g. temperature, length).
• vector (e.g. glacial ice velocities).
• matrix (e.g. stress states).

What are fundamental measures in physical science:

• length
• time.
• mass.
• volume.
• position in a coordinate system.
• pressure.
• temperature.
• composition.
• these can generate other more complex quantities (e.g.velocity, or a stress state).

Examples of environmental data?

In class exercise: You will get into groups of 4-5 and be given a map, or you can bring one to class. Use it and the material discussed so far to answer the following questions (We plan for this to take about 15-20 minutes).

• What space is being mapped?
• What features or information is being mapped in that space?
• Words are used to communicate in text - what equivalents exist for your map?
• From an environmental perspective how might the information displayed be relevant?
• What patterns can you see in your map?
• What might be factors influencing that pattern?
• What decisions went into making the map?
• How might the map be improved? Think of what might be deleted in addition to what might be added.

Be prepared to discuss your results in class.

Why are maps important in environmental science and endeavors?

• allow us to visualize things we can't see.
• helps us to recognize patterns.
• attempt at higher level of truthfulness (test of mental maps).
• permit further quantification.
• much more efficient form of communication and data archival.

Definitions of a map:

Clarke: "A depiction of all or part of the earth or other geographic phenomenon as a set of symbols and at a scale whose representative fraction is less than 1:1."

Glossary of geology: " A graphic representation , usually on a flat surface, of selected physical features (natural, artificial or both) of a part of the whole of the surface of the earth, some other planet, the Moon, or any desired surface or subsurface area, by means of signs and symbols and with the means of orientation indicated, so that the relative positiona and size of each feature on the maps corresponds to is correct geographic situation according to a definite established scale and projection."

Webster dictionary: "a representation, ususally on a flat surface, of the whole or part of an area."

Harley and Woodward: "graphic representation that facilitate a spatial understanding of things, concepts, conditions, processes or events in the human world."

Harmon's: An image depicting the distribution and or position of a feature or features in some sort of space.

Genetic maps, geologic maps, geographic maps, phase maps, computer maps, mental maps - the list goes on. How many more maps types can you add?

Graphs as maps or maps as graphs?

• x,y,z variable space.
• pressure and temperature (x and y) space for a phase map.
• for most maps x and y are geographic coordinates, and z is elevation above sea level (a topographic map, DEMs - described below).
• geographic coordinates:
• latitude and longitude.
• UTM, easting and northing in meters from a reference point.
• spherical to flat surface necessitates a geoide and a projection.
• GPS revolution.
• x and y as geographic coordinates and z as a state variable such as T.
• many other possibilities.

What is being mapped?

• discrete objects or points.
• density of discrete objects or points in space.
• continuous surfaces.

Spatial patterns of point distributions:

• random vs. nonrandom.
• clustered vs. anticlustered.
• regular.
• fractal.
• anisotropic vs. isotropic.
• what type of pattern exists below?

Contouring a continuous surface from point sampling:

The most common type of contour map of a continuous surface you might be familiar with are USGS topographic maps. These are widely used and distributed. However, there are many other examples of contour maps.

Imagine you would like to know what the distribution of a toxic compound is in ground water in an area. You can drill wells and take samples and have them analyzed for how concentrated a given toxin was in a sample from a given well. But what is the larger hidden pattern of toxin concentration invisible to the eye, but sampled by the wells. You might imagine putting a drop of dye in water to represent a point source of toxin in the ground. The dye spreads with time. The concentration of the dye and the color of the water will at first be greatest right at the source, and diminish with distance. A contour line is simply a line that separates one part of a surface where values are higher than the contour line value from the other part where values are lower. Contour lines of concentration and/or color would produce a bullseye pattern around the source. Contaminants in groundwater can move in additional ways to simple diffusion (which is what happens in the case above), and thus the pattern of the contours can vary from this pattern. We can contour the values of the toxin concentration for the wells to visualize what is happening in the ground. A simple rule is that a given contour line for a given concentration needs to consistently separate wells (points) that are higher than the contour line value from those that are lower. In addition, contour lines can't cross. It is useful to practice hand contouring to gain real understanding. This is a link to a practice exercise.

Surfer and other software programs will contour more systematically than doing it by hand.

DEMs (Digital Elevation Models) are gridded files of elevation, and are used for better understanding topography and earth processes. Computer programs can turn them into shaded relief images.

Above is a shaded relief image of elevations from part of Nebraska. From the top to bottom boundary of the image is about 8.8 miles. Where in Nebraska do you think this comes from? Why? What type of landscape features are depicted here? What environmental significance does this landscape have?

Some examples.

References:

Clarke, 2000, Getting Started with Geographic Information Systems; Prentice Hall, 352 p..