Sinkhole Risk in Missouri

Sinkholes have become a topic of renewed interest in various parts of the country; specifically, in Missouri where some areas have noticed an increase of phenomenon. However, this type of geologic formation has not been given the same level of attention as more exciting geology, such as volcanoes and earthquakes. It has remained mostly misunderstood and understudied, except by the few that have devoted their life’s work to the study of the type of terrain harboring them, known as karst.

Beneath the state of Missouri is one of the largest, most continuous karst terrains known.  It is primarily created by dissolution of rock, sometimes leaving the landscape looking pockmarked, and a bit “like Swiss cheese.”  (Robinson, 2006) Natural springs, magnificent cave structures, and complex underground river systems characterize this landscape; as well as hidden dangers, such as deep vertical shafts and sinkholes.  Usually sinkholes, sometimes referred to as collapses, form slowly and on such an insignificant scale, that they seldom affect everyday life.  (Kauffman, 2007) However, sinkholes can form suddenly, sometimes on a massive scale, and with devastating consequences.

Natural sinkholes typically form where the underlying bedrock is composed primarily of fractured limestone and dolomite, from as far back as 500 million years ago.  (Elliot, 2008)  As water trickles down through the soil, this underlying bedrock erodes away, leaving an empty cavity.  Combined with sediment particles, the infiltrating water continues to erode the bedrock, creating its own path through the varying layers of sedimentary rock, widening and opening the cavity as it goes.  (Kauffman, 2007)  It is hard to predict what will happen next in this equation.  It may develop a huge cave that continues to expand for millions of years, sustaining a unique and alien ecosystem of its own, a sinkhole could develop, or both.

The United States Geological Survey identifies two different types of sinkholes.  The most benign are solution and cover-subsidence sinkholes, which are usually nothing more than an inconvenience.  The ground above the eroding rock layers slowly sinks into the cavity, forming a small surface depression.  This process might stop or may continue repeatedly over hundreds of thousands of years in the same location, with only incremental changes to the overall surface structure.  

The second type is a cover-collapse sinkhole, which is the biggest concern, because they often develop quickly and unexpectedly.  These sinkholes usually develop where the ground above the bedrock is comprised of a significant amount of clay or simply can no longer withstand the weight above.  As the water and sedimentary particles filter through, and erode the underlying bedrock, the clay remains in place above, forming an arch-like structure, or cavern.  These caverns can be just a few feet wide and deep, or hundreds of feet in depth and width.  As erosion of the overlying materials continues, the roof of the cavern progressively collapses in on itself until it eventually reaches the surface, and the entire structure collapses.  (Kauffman, 2007)  

From 1970 to current date, the Missouri Department of Natural Resources investigated nearly 200 reported collapses, and found that most were less than 10 feet in diameter and depth.  (Kauffman, 2007)  However, there have been some documented that have covered numerous acres, and have caused massive property and ecosystem damage.  Recently in Missouri, there have been a few cities which have been experiencing an increase of the appearance of this nuisance; indeed, just a few years ago, an entire lake recently disappeared because as the result of a sinkhole.

Surrounded by a suburban subdivision, the 23-acre Lake Chesterfield in St. Louis drained in just a few days in 2004, after a sinkhole emerged in the lakebed.  (Currier, 2004) The man-made lake, and accompanying subdivision were built in the mid-1980s.  The only reported review of the structural integrity of the area had been through aerial photos taken by the county.  The photos did not indicate the presence of past sinkhole formation, or that the landscape would be prone to this sort of development.  As Glenn Powers, planning director for St. Louis County indicated, “These things happen.”  (Price, 2004) If there had been a minor, hidden collapse, it may have gone unnoticed by developers.  The water from the lake might have begun to seep into a small crack around an old overgrown sinkhole and only leaked out a thimble full of water every day for years, until just enough erosion occurred.  

In this scenario, once it reaches this point, it is much like someone pulling a plug on drain.  The Missouri Department of Natural Resources (MoDNR, 2004) reviewed this particular case, and found that the rock layers underlying lake were very “prone to solution activity.”  (MoDNR-176, 2008) This indicates that the areas have always been a prime candidate for sinkhole development, and intensive studies should have probably been done, prior to any development.  

Plans are being made to seal the sinkhole and refill the lake, at great cost to the homeowners of the subdivision.  As private property, the city is not obligated to restore the lake, or repair any damages done.  This is not an isolated episode, either.  Property owners are facing growing repair costs, as the incidents increase, especially in the southern part of the state, where karst terrain is most dominant.

Near Springfield, in 2006 a sinkhole measuring approximately 60 feet wide and 75 feet deep, opened and swallowed portions of a couple of homes in a half-block area in Nixa, Missouri.  One homeowner that lost half of house said that he had been reading the paper, when he heard a rumbling noise.  Initially, he thought that it was a thunder or something similar.  He was surprised to look out of his window and see part of his house, garage, and car swallowed by the earth.  

City spokesman, Bryan Newberry stated, “These homes had been there without problems until this point.”  (AP, 2006)  This is typical of sinkhole formation; they do not send up a warning flare prior to their arrival.  Small towns like Nixa and rural areas are ill prepared for situations such like this.  Building codes are either not in place, or because the construction is technically outside of city limits, do not apply.  

In a recent Geographic Information Systems (GIS) analysis, which accompanies this article, it was discovered that there are areas within Missouri, which are at a higher risk than others are, and Nixa is no exception.  Situated just a few miles immediately south of Springfield, the city sits squarely on one of these higher risk areas, and as recent as April 2008, new sinkholes have begun to form.  There are no existing regulations requiring developers to conduct research on the geology before construction.  Nixa city leaders have taken notice though and are beginning to discuss how to address the issue, considering changes to regulations concerning construction around sinkholes.  (KY3, 2008)

Another city, which has also been witnessing a steady increase in sinkhole activity, is Cape Girardeau.  As of April 2008, the city has recorded 20 collapses over the past nine months.  According to Ken Eftnick, Director of Development Services for the city, they “have been seeing one show up every week or so and don’t anticipate that changing anytime soon.”  (McNichol, 2008)  

Workers in the city continue efforts to stabilize and fill the sinkholes, but there really is no good way to fill a sinkhole and be certain it will not reappear.  They are finding it difficult to keep up though, as heavy rains and flooding continue in low-lying areas of the Mississippi River, near the Cape.  Documenting the sinkholes, through site visits and aerial photography, the Geographic Information Systems Coordinator for Cape Girardeau continues to attempt to make sense of it all.  The holes do appear related, and the cause is still a mystery, while property owner concerns mount.  

The biggest concern for the city is a wastewater treatment facility, which lies perilously close to the area that the collapses have been occurring.  Widespread contamination of precious groundwater and ecosystems would then be the biggest concern, should a collapse occur beneath this facility.  (Arnand, 2008) In the meantime, industry is adjusting.  Utility lines, both gas and electric, have had to be moved and Burlington-Northern Sante Fe Railroad has installed ground movement sensors to alert oncoming trains if there has been significant disturbance to the integrity of the rails.  At the local rock quarry, it is business as usual.

Sinkholes can be problematic enough without human intervention.  Research has drawn correlations between some of these sinkholes and human land-use practices, specifically as they relate to ground water pumping.  (Barnett, 2007)  In this case, the water pumped out is acting as buoyant for the ground surface above, helping it to maintain a relative degree of structural integrity.  When ground water is pumped out, the earth above it no longer has any sort of support, and the structure could collapse.  The same effect may be occurring in Cape Girardeau, with the river acting as the pump.  Higher than average precipitation and flooding could be the catalyst, causing the Mississippi River and its tributaries to swell and recede.  This action fills the gaps in the rock underground, and stabilizes it somewhat.  When the water retreats though, it leaves only air to support the ground above, disrupting previous structural integrity.  In addition, earth movement from minor earthquakes, as well as human disturbances, intensify shifting.

Cape LeCroix Creek, around which many of the sinkholes have been developing, indirectly empties into the Buzzi Unicem quarry.  Water from the creek disappears underground and reappears in the walls of the quarry, further eroding the rock layers during its underground journey.  Regular blasting at the quarry site may be compounding the problem.  When asked about the significance of the nearby quarry activity, the GIS coordinator for Cape Girardeau dismissed the idea as not particularly relevant to the current situation, and that the blasting was insignificant.  (Arnand, 2008) However, a visiting geology professor noted that there was regular significant scale blasting occurring at the quarry, and that alone could be enough to create the problem.  He indicated that during his brief visit, he could feel vibrations from the blasting, as much as a mile away.  (Hageman, 2008) Similar to a carefully balanced house of cards, these intense vibrations can cause the loose layers of rock to shift and settle.  Water may intrude, washing away particles that have filled gaps, and when blasting resumes, the underlying rock settles further.  If a significant gap opens in the rock layers under the ground, it could cause those rocks to shift and settle, resulting in a collapse.  

While scientists are known to not agree on just about everything from A to Z, this does lead to an interesting question.  Given the set of circumstances, is it possible that the public is being put at risk, in the interests of preserving a business, which is the “biggest employer and highest taxpayer in Cape Girardeau?”  (McNichol, 2008) There is no question that in order to dismiss the quarry as an antagonist to the problem, an impartial study should be conducted in and around the quarry.  The city recently reached out to the U.S. Army Corps of Engineers, to help identify and propose remediation to the problem.  

The U.S. Army Corps of Engineers will have its hands full, investigating the exact cause of the sudden increase in sinkhole activity.  For years, karst landscapes were ignored, except by mining and industry interests.  A notable few have done extensive studies, but when compared with other types of terrain, research has been lacking.  Perhaps, it has been the level of accessibility, or simply the basic assumption by everyday people that the ground is as solid as it will always be.  In either case, situations such as those in Cape Girardeau, have demanded that scientists turn their attention to the topic.  At the time that this article was initiated, there was very little to be found about sinkholes, excepting news reports, and a few in-depth geologic studies.  Since that time, numerous new studies have appeared each with their own hypothesis on the exact nature of this problem, and with a different approach to solving it.

The initial GIS analysis and mapping done in combination with this article reviewed the rock layers within Missouri, and their relationship to sinkhole incidents Using the latest GIS software, two separate analyses were conducted (refer to analysis maps at end of article).  The study only scratched the surface; excepting geology, no other factors that contribute to sinkhole development were considered in the analysis.  As with any science, confirmation of previous findings is essential to forming a solid base for future research.  The analysis did confirm that the state is indeed “textbook karst.”  (Elliott, 2008) The regions with the highest incident of sinkhole activity are comprised of Paleozoic era, Cambrian, Mississippian, and Ordovician systems.  These are some of the weakest rocks, when pitted against the scouring power of running water.  Future research can use the study as base to continue comparisons with the other factors, in order to narrow down the possibilities until a specific cause is identified.

Identifying the cause of sinkhole development could take years.  Many of the factors that contribute to this problem are not constants, and monitoring of these phenomenon will be essential in understanding their significance.  Until a cause and permanent solution can be agreed upon, there are measures that individuals living in affected areas can take to avoid the problems associated with these formations and avoid the disaster that has befallen some of the previously mentioned communities.  

the state of Missouri should initiate a thorough investigation of its karst regions and make recommendations to the local governments to regulate construction in these areas.  The local governments could then work towards identifying their own specific areas of concern and inform their citizens of potential hazards.  Findings should be communicated quickly, and in comprehensible terms.  As Assistant Professor of Geography, David Fox of Park University indicated during a brief interview, it is important that the message about geographic dangers “be communicated effectively to the general population [and] focus on real people and their personal relationship with the environment, so that they walk away with a better understanding of the impact.”  (2008)  Indeed, with a better understanding, there will be a lot fewer surprises, and might just save a life.  At minimum, property owners can take charge of the situation themselves, and attempt to understand the structural integrity of their property, and insure themselves appropriately.  Only through awareness, will sinkholes be more understood, and their effects on human habitation, be minimized. 

 References

• Elliott, William R.  Below Missouri Karst.  [article online]  Missouri Conservationist 2000 Mar:61-3. http://mdc.mo.gov/conmag/2000/03/10.htm.  Accessed 2008 Mar 28.
• Currier, Joel.  Sinkhole quickly drains 23-acre lake in Wildwood. [article online] Jun 11, 2004.  St. Louis Post-Dispatch.  Available from http://www.ambrosiasw.com/forums/lofiversion/index.php/t44593.html.  Accessed 2008 Mar 29.
• Kauffman, James E.  Sinkholes.  [article online]  July 2007.  United States Geological Survey Fact Sheet 2007-3060.  Available from:  http://pubs.usgs.gov/fs/2007/3060/pdf/FS2007-3060.pdf.  Accessed 2008 Mar 29.
• Sinkhole Formation.  [article online]  2008.  Missouri Department of Natural Resources:  Division of Geology and Land Survey.  Available from  http://www.dnr.mo.gov/geology/geosrv/geores/sinkhole_formation.htm.  Accessed 2008 Apr 3.
• Price, Peter and Sturgess, Steve.  Lake Chesterfield Sinkhole Formation. [article online]  June 17, 2004.  Missouri Department of Natural Resources News Release No. 176; Volume 32-176.  Available from:  http://www.dnr.mo.gov/newsrel/nr04_176.htm.  Accessed 29 Apr 2008
• Associated Press.  Home swallowed by giant sinkhole.  [article online]  August 14, 2006. Columbia Daily Tribune.  Available from:  http://www.columbiatribune.com/2006/Aug/20060814News010.asp.  Accessed 2008 Mar 30.
• Underground Ozarks. [photo online] August 14, 2006. Nixa Sinkhole.  Available from:  http://undergroundozarks.com/blog/index.php/2006/08/14/nixa_sinkhole  Accessed 2008 Apr 27.
• Robinson, Jonathan L. Sinkhole collapses in Nixa, Missouri; SCI Engineering investigates.  [article online]  August 22, 2006.  SCI Engineering, Inc.  Available from:  http://www.sciengineering.com/pressrelease/Nixa%20sinkhole%20collapse%208-25.pdf. Accessed 2008 Apr 30.
• Latest sinkhole could cause change in Nixa building rules.  [article online]  April 7, 2008.  KY3 News.  Available from: http://www.ky3.com/news/local/17366234.html. Accessed 2007 Apr 30.
• McNichol, Peg.  Cape sinkhole total reaches 20 as five more appear.  [article online] April 13, 2008. Southeast Missourian.  Available from: http://www.semissourian.com/apps/pbcs.dll/article?AID=/20080413/NEWS01/780792621/0/NEWS03.  Accessed 2008 Apr 30
• Barnett, Cynthia.  Exceprt from Mirage:  Florida and the Vanishing Water of the Eastern US.  [article online]  2007.  Available from:  http://www.npr.org/templates/story/story.php?storyId=11097869 .  Accessed 2008 Mar 30.
• DATA:  Missouri Spatial Data Information Service. http://msdis.missouri.edu.  Accessed 2008 March.
• Fox, David.  Personal Interview. 27 Mar 2008.
• Hageman, Scott.  Personal Interview.  24 Apr 2008
• Arnand, Annie.  Telephone Interview. 21 Apr 2008

EN306C: Advanced Expository and Research Writing

3rd Annual Research & Creative Arts Symposium

Fatality on the Home Front

My “Fatality on the Home Front” Map displays the distribution of fatalities of the war in Iraq, according to their home state in the United States, in relation to the number of recruits from each state in 2004.  

The data for fatalities was collected from a well-referenced media source, iCasualties.com.  The data was imported to an Excel spreadsheet, where some fields needed standardization to remove anomalies, such as extra spaces before names.  A new field was added to provide a state abbreviation, since the “Place Name” that the database was to be geocoded against, had abbreviations and not full names.  All entries for individuals from outside of the 50 states were removed from the database, for simplification, and the database was ready to be geocoded.  The Place Name file was chosen from NationalAtlas.gov, an Address Locater was created, and the Fatality database was geocoded against that.  There were approximately 500 entries that had to be matched interactively.  After each of these cities located in Google Maps, the nearest city within each state, appearing in the Place Name file, was chosen to match against.

The geocoding results were then plotted on a base map of the United States, provided by NationalAtlas.gov.  Since point data can really only be displayed as points, I realized that I needed something for comparison.  First, I attempted to compare it to general population figures, but the numbers were too insignificant.  Then, I attempted to locate armed forces census data but discovered that their job profiles are buried in the regular job profiles of the census.  After much consideration, and a lot of searching, I discovered the 2004 new recruit data on StateMaster.gov.  I attempted to locate a wider range, but unfortunately the Department of Defense does not share that type of information, and it is not available in normal Census data.  I decided that since that was the first full year after the start of the war in Iraq, it would be an adequate statistic to measure against. 

Comparing the number of fatalities to the number of new recruits was relatively easy in ArcGIS, but the balance of the cartographic design was not so easy.  The first consideration was the thematic overly, or map type.  I chose a graduated color map, because I believe it displays data on a national level much more effectively than any other type of symbol map.  It is easy to see patterns and pick out disparities in the data.  For this, I believe it worked very well.  The second biggest consideration was a color ramp.  I wanted something that would go well with the data and represent something close to the idea of a fatality.  After sifting through each of the color ramps provided in ArcGIS, I decided on the one that had the deepest color of red, closest to that of blood, to signify the loss of the same.  I was not entirely happy with the pink at the low end, but in the scheme of things, it worked out to signify what it should; there was very little loss of blood/life.

The remainder of the design was primarily towards technical aspects.  Initially, I tried a graticule, but it seemed to interfere too much, so I discarded it.  For the purpose of this map, it was not particularly relevant, so much as the data in the map itself.  I also had Alaska and Hawaii represented, but they too interfered with being able to balance the map and the textual information adequately.  Since the numbers for these states were not particularly outstanding, I decided it would be just as well to display their specific numbers in a relative position on the map page.  Part of this might have been due to the projection chosen, but I feel as though I might have had the same problem no matter which project I choose.  The final choice for projection was Albers Equal Area Conic, since it is one of the accepted norms for representing the conterminous United States.  The legend became a small problem, after some inspection.  The data was not represented accurately in the first draft, because the numbers were whole numbers.  While this would be perfectly acceptable for the intended audience of the map, for data representation it was lacking a bit, and the legend was adjusted to display two decimal places.

The balance of the map page is mostly aesthetic.  For appearance alone, the major lakes of the United States were chosen, but later I realized that it completed the map’s representation of the “red, white & blue.”  The scale bar chosen displays a singular numerical width of 1000 kilometers.  Kilometers were chosen because it is the international standard, and I believe that all measures should correlate with those standards.  Label were placed on the states, though a few had to modified for appearance, such as Vermont and New Hampshire; their abbreviation is displayed.  The north arrow was chosen for its appearance, and to provide a general sense of direction.  The title and subtitle were chosen to reflect the appearance of the intended audience, a general news readership.  Text was discriminately for details about the data and its sources, and the Arial font for its clean and neat appearance.

The overall layout was simple and straightforward.  I chose a thin, unobtrusive neat line to border the map page at one inch from the margins.  All elements were arranged within the neat line for a good sense of balance.  In order to make the text stand out better, a slight drop shadow was added, kerning adjusted to 2 pixels, and a fine black “stroke over fill” edge added. For a finishing touch, I added the stock photo of an American flag, for a backdrop.  This photo was made to be mostly faded and transparent, so as not to distract from the content of the map page, while still giving the map a sense of patriotism, and honor those that had fallen.  

GGP330 - Cartography
3rd Annual Research & Creative Arts Symposium

Cave Density in Missouri Counties

This map arose from a GIS project on sinkhole development.  I created during that time, but really did nothing special to it.  It was created to display the varying density of caves in the state of Missouri. so that I might observe their relationship to sinkhole development.  

The data for this map were collected from the Missouri Spatial Data Information Service (MSDIS), and it seems just in the knick of time.  The shapefile I had originally downloaded is no longer available from their service.  Fortunately, there is not much of a contrast between the sinkholes and caves.  They both pretty much exist in the same circumstances.

The manner in which this map was created is slightly fascinating to me.  Essentially, it displays the spatial join of a County shapefile and a Cave Density by Quadrangle polygon (not points) shapefile.  MSDIS indicated that the reason the Cave Density file is shown in this manner, to protect the locations of private and dangerous caves.  Regardless, the two files were joined, and I chose a dot density format for display.  Initially, I did this just to see if the software would do it.  After I discovered that it would, I played with the density options, and discovered that I could “mask” the dots to the original quadrangle file, for a greater degree of accuracy.  Indeed, I perceive it to have done just that, and the distribution appears to be very similar to sinkhole locations.

While struggling to figure out what I was going to do for this assignment, I rediscovered this map, but was at a loss as to how to spice it up.  I tried several things, inserting lakes, rivers, cities, etc, but nothing really seemed to fit with this map.  It was almost as if it demanded to be left in its most raw format.  Consequently, I decided it would be a simple and basic cartographic display of dot density, by county; and actually, by quadrangle.

I choose the color for the counties because it is somewhat of a standard color in maps of this type.  It is non-intrusive to the data, and not distracting in the least.  Actually, it was simply “beige,” but I decided that even that was too much of a glare, and imposed a 50% transparency.  The only other item I could think to add to the map was the county names, for better location comprehension.

Stepping outside of the usual choices, which I had made in other maps, for scale and north arrow; I chose something just a little different.  The north arrow, with a simple northern indicator was really all that was needed, and it was obvious.  However, my own choice of scale bar surprised me in its effectiveness.  By dicing up the division in the intervals that I did, and the alternating “low/high” effect it has, created a simple scale bar that is very easy to visually translate to the map, without having to pinch your fingers together, or get out a ruler.  The remainder of the map is simply title and data credits.  The projection was also added, as Transverse Mercator, likely the best projection for the state of Missouri.  The only issue I had, which I still do not care for, is the legend.

I found the legend be particularly annoying.  Every time the legend is moved, the dots move around inside the box.  That is not so much the problem, as ArcGIS forces the user to have an extra unnecessary item, that which the dots represent.  It seems enough to have “1 dot = 5;” I can always tack “caves” to the end of that with the built-in tool set.  I do not see the necessity for that, but perhaps I do not understand it enough, or I am completely missing how to rid myself of that extra line.  In either case, I could have easily erased it in Photoshop, but thought that it might have some significance that I was missing. 

Finally, I noticed that the map did not really fit the page nicely, no matter where I placed the elements.  Ultimately, I decided that it would be a square sheet, for no other reason than to contain all of the elements more nicely.  In addition, as with every map, the final product was created ready for press, in 300 dpi JPG image format.

Overall, with an understanding of how it was created, I find this to be an interesting map and would be very curious to know how accurate the dots are in relation to actual cave sites.

GGP330 - Cartography

Square Kilometers per Person

I initially conceived this map while trying different things with world data but decided to add a different twist to the manner in which the data was displayed.  Most people choose to display this type of data as “persons per sq km,” and I decided to do the exact opposite, to see how much space there is for people of each country.

The data for this map were collected from that which accompanied the software for ArcGIS, by Environmental Systems Research Institute, Inc. (ESRI).  It is a simple join between population and country data, and I found it to be a rather interesting display, though I usually do not care for these types of symbols on maps.  They always seem too difficult to ascertain exactly what is going on in the map, unless there is a huge disparity.

I encountered a problem right away, when I chose the proportional symbol.  All of the symbols were so big that they covered most of every country.  I quickly figured out that I could scale down the size of the initial symbol, so that the rest were not so obtuse, and was quickly on my way to creating the rest of the map.  The only thing that still concerns me is the relative size of the lower numerically represented symbols.

The color that I chose to represent the base was a little more complicated, and I ended up using two separate world layers to get the effect that I wanted.  I thought that the continents should be green, symbolizing mostly habitable areas on the planet, while at the same time, I expected Antarctica to show up as white, since there is usually snow there all the time; thus, the two layers, one white, the other green.  It was at this point, that I chose the symbol color.  Yellow seemed to be the obvious choice.  It typically means happiness, and I figured that the more space there was for each person, the happier they would be, so it was good fit.

The background gave me a small problem.  While it was easy enough to turn the oceans blue, it also turned the entire background of the map blue.  There was no way to distinguish where the earth left off, and the canvas began.  Initially, I tried adding a graticule.  After reviewing it, there was some sense to having it, to understand the distortion in the projection that was taking place.  However, it really did nothing to offset the earth.  Ultimately, after the map was completed in ArcGIS, I imported it to Photoshop and dissolved the background around the globe.  I changed the background to a light gray and left it at that.

The projection was a little difficult to come to terms with as well.  I tried several, but they distorted area too much, or a few of symbols completely obliterated the areas they represented.  In a final act of desperation, I turned to the Cartography book and discovered my answer there.  It indicated that the Winkel III World Projection was a good one to use, so I went with that.  It still did not fit the situation though.  Countries were still being blocked out by symbols.  However, the Winkel II worked perfectly to preserve area and distance, while preventing countries from disappearing under symbols too much.  Greenland, Svalbard, and the Falkland Islands still have this problem.

Another problem I encountered was label placement.  Ultimately, I raised the symbol weight on the features to a point that they finally began to show only the most prominent relevant features.  In addition, since there were really no oceans in the shapefile, I had to add the labeling for those independently.  In addition, since the countries previously mentioned were obliterated by the symbols, I went through and manually added labels on top of those symbols, for easier recognition.

At this point, the remainder of the map was rather straightforward and simplistic.  A self-explanatory title was added, along with the data credits, as well as the legend.  As with most legends, I declined to label it as a “Legend;" it just seems silly, unless there is so much activity on the map page that you cannot discern the legend from the map.  Of course, in that case, it might be better to start over with a new map.

Finally, the final product was created ready for press, in 300 dpi JPG image format.  The results were rather surprising though.  I did not expect to see such a difference in the US and many of the other countries.  However, I believe that this data to be heavily weighted towards the three obvious places with the most area per person.  If those were removed, the map might show a completely different picture.

Overall, much like graduated symbols, I still do not care for these types of maps.  I suppose that it might prove useful for displaying some data, but this is probably not the best format for its display.  It does show some recognizable trends though, that would be more apparently in graduated color map.  

GGP330 - Cartography

Population Change in Census Tracts

The purpose of this map is to display changes in population between the 1990 Census and 2000 Census of Buchanan, Clinton, Platte, and Clay Counties.  I conceived this map upon hearing about Park University’s Northwest Missouri Deep Map Project, and thought it might be an interesting type of data to display.

The data for this map were collected from the Missouri Spatial Data Information Service (MSDIS), as well as the National Atlas.  The later was only to obtain the state of Kansas for display purposes.  Essentially, it is a simple join between the census tract data, a census tract shapefile.  The counties were added from the state of Missouri to better define the census tracts, and the state of Kansas, purely for aesthetic purposes.

The base map colors were chosen to be a slightly graduated scale, for easier interpretation, and separation.  The color for Missouri is actually the same as that for Kansas, except the later displays a 50% transparency.  The symbol for the color seemed an obvious choice; it needed to be something that contrasted well with browns and tans, but did not raise any alarms.  After cycling through several different color choices, green seemed to fit the best.

Once displayed, I found it somewhat interesting that the map was showing minimal growth towards Jackson County, in Clay County; at the same time, it was showing large growth towards Jackson County, and little growth in the northwest regions of Platte County.  I am quite sure that has changed significantly, since the 2000 census, and will be interested to see how that comes out when the 2010 census data is made available.

Choosing the symbol size was not particularly difficult, but I did have some difficulty understanding whether it was appropriate to display negative enumeration units consistent with those that are positive.  In the end, I decided it probably did not make that much of a difference, as long as it was accurately represented.

Much like the Cave Density map I produced, the layout is simple and straightforward.  It was with that map and this one, that I decided that I wanted to explore the graphics potential of ArcGIS, more than I had already.  I made several discoveries, about placing, and aligning things that I forgotten about.  Ultimately, I was glad that I took the time to do these final maps in ArcGIS alone, rather than importing them into Fireworks or Photoshop for final touch-ups. 

The remainder of the map was a series of obvious choices, to me.  The north arrow was added to aid in directional understanding.  Data source and credits were added, along with the title, which did give me a little bit of trouble.  Primarily, I was unsure as to what to call the map.  I had initially made the subtitle “Park University’s Deep Map Project Area,” but discovered that the area actually encompasses over 20 counties.  This deep into the map, I did not particularly want to go back to square one, but could have very easily done that.  This seemed like the best and most simple area of study, so I stuck with it.

In looking over the near-final product, I decided that the counties names needed to be a little bigger, to be seen as distinct from the surrounding counties.  As well, the focus of the data frame needed to portray the counties of study, and their immediately adjacent counties and/or state.  My favorite type of scale bar was added, as always in kilometers, because I feel that the US really needs to get on board with the metric system.  Otherwise, this type of scale bar is my favorite because it is easy to pinch with your fingers, or lay your thumbnail to, and take to a different location on the page. 

There were a couple of things that gave me some trouble on this map though.  The projection was a trial and error situation.  Nearly every projection that I tried on this caused a slanting, which remains every so slightly, still.  However, the North America Albers Equal Area Conic Projection was the one that seemed to maintain direction and area the best, after trying ten or fifteen.  In addition, where and how to place the state names was a little difficult, but after stepping away for a bit, I realized that the most logical place, was at the bottom center, between the state lines.  Finally, I chose a simply neat line to surround it all, after cycling through every one available.  It seemed that this was the one meant for the page.

Overall, I still do not particularly care for these types of maps.  When I initially displayed the map in graduated color, the changes were much more obvious.  If I had my choice on doing it again, I would choose the later.  Otherwise, as every map should be, the final product was created ready for press, in 300 dpi JPG image format.

GGP330 - Cartography