Category: Practicum

How might you use this georeferenced image to uncover new information about the history of the region you just mapped?

While working on this image I found myself noticing two new things to think about. First, the movement of water, in the maps the rivers might look slightly different, but also how much the shapes of the lakes had changed. In some places like south central where there is a lot of lake small lakes this was especially evident. Another new piece of information I noticed was the changing of county lines, especially in the far north area of the state. Some lines moved, while other whole new counties had been formed in the 100+ years between the map’s creation. Using two exact points in time helps show a distinct comparison, compared to a map that shows gradual over time. I think that using just two points in time on a  map makes the map easier to digest as well.

 What are some weaknesses to this approach? Are there inaccuracies? Do some places map better than others? Why?

One of the first things that comes to mind is how much we have improved technologically since the creation of many older maps. Now, we have access to satellite images to create or cross-reference maps with. However, prior to only a few decades ago, you could not. As a result, a geographer might map something 5 miles off from where it is, if there was an error of some sort in their measuring. While this wasn’t an issue with my map, I can imagine that the older the map, the easier it could have been to make mistakes like this. The map that I chose covers a relatively large area so I felt that it might be easier to place a reference point in a place that is a few hundred years off from where the reference point that I placed on the Google map. Compared to a smaller map where it would be easier to find the exact point, especially on the older map.

The map I overlaid onto a present-day Google Maps view of Colorado seems to be primarily artistic in nature with geographic accuracy taking a backseat to the inclusion of historical anecdotes and images on the map to recount parts of Colorado’s history. This map’s primarily artistic and historic focus reveals how people viewed Colorado and remembered the state’s history around 1935, the year in which this map was published. Its lack of geographic accuracy as compared to Google Maps reveals how precise distance and geography were likely not seen as vital parts of Colorado’s history in comparison to chronicling milestones of the state’s history and highlighting the stories of historically important cities and people in Colorado. It seems that the history of Colorado in popular memory, at least in 1935, was based upon presenting great people, events, and stories in an appealing and flowing narrative. In this way, this map provides an excellent window into the popular historiography of Colorado when compared to a present-day map of the state.

One weakness of georeferencing is that some maps are difficult to read when overlaid on another map. The map I overlaid in this activity includes a substantial amount of text that is relatively small in size. When overlaid on another map, this small text because almost unreadable unless you zoom in an enormous amount. This text can also obscure features on other map layers even when the overlaid map is somewhat transparent.

There are some inaccuracies with georeferencing because of the distortion a map undergoes when it is georeferenced onto another map. Some elements are distorted in the process, altering the original structure of the map the mapmaker intended readers to see. This can hinder the study of a map as a window into the perception of the mapmaker on the mapped area.

Some places with relatively unchanging landmarks would map much better in a georeferencing system than areas with constantly changing features. Rivers, roads, and building, among other landmarks, have locations that can change significantly over time. Places that have undergone minimal change throughout the time between when the layered maps were produced are most conducive to georeferencing as inaccuracies and distortions can be minimized. However, georeferencing maps of regions that have undergone significant change can provide an excellent opportunity for comparing maps and analyzing how the physical terrain and the priorities of mapmakers have changed over time.

Overlapping multiple layers of maps can be very beneficial: in this case, and many other examples, I believe it is best used to experience/note change over time. The layered map (sitting on top of the google map base) has Haleakala National Park of Hawaii labeled in red. Over 60 years later, it would be very easy to indicate either the expansion of such reserve or the decrease in size. I would hope the reserve has increased in size from the 1962 map as maintenance and preservation of biodiversity grows in importance. Second, as ice caps begin to melt and ocean levels rise, this map would provide great insight into this change as depths and contour lines of shoreline/reef structures are highlighted. This could help to examine change over time as climate conditions continue to shift. The red lines highlight, what I presume to be, the main highway that encompasses the island of Maui. There would be a great change in this system as infrastructure seems to be on an exponential expansion destroying everything in its path. 

As different maps undoubtedly have different scales, this scaling may throw off the true shape of the location the map focuses on. When this occurs, it may make it hard to accurately overlay two maps and ensure that one point on one lines up with one on the other. Further, as technology advances the accuracy of mapping does as well. When comparing a map from 60+ years ago, as I did, to a never-ending data mine (google maps), there will definitely be some differences in borders, town locations, streets, etc. In this case, my map was created by the US Army so I believe their technology at the time would have been the most advanced, possibly not even available to the public. However, maps today are certainly more accurate than the best of the 1960s. This may make it hard to georeference one map onto another–simply based on inaccuracies and changes. As seen in my example, there is a stretch of highway running over the ocean in the bottom-middle region of the island; when in reality this does not happen. There was simply no way to accurately depict the entire shoreline, and this stretch took the biggest hit. Using 7 control points was not enough to layer these maps together, I had to use nearly 20–a definite weakness of this approach. I am wondering if there is a way to trace a border and layer them together by that–I feel like that would be a much more accurate, but tedious, method. Overall, I am satisfied with how the georeference came out: but it is certainly not a 1:1 scale.

1. How might you use this georeferenced image to uncover new information about the history of the region you just mapped.

When comparing an older map to today’s Google Maps, changes in the region over time become apparent. Even in an older city like Rome, there have been changes since the creation of the map to today. In addition, this approach of georegerenced images can be helpful to have a more indepth understanding of the streets within the region. For example, the neighborhood of Trastevere, which lies on the other side of the Tiber, is hardly depicted in the original map. However, when layed with Google Maps, the viewer gains a more indepth understanding of the neighborhood as its vast network of streets. Similar to this, neighborhoods on the outskirts of Rome come into view when layered with Google Maps.

2. What are some weaknesses to this approach? Are there inaccuracies? Do some places map better than others? Why?

One weakness to this approach is that one of the two maps may have inaccuracies. When creating the older map, the author might not have had all the resources we have today to make accurate decisions about where to place its features. This leads into the idea of how some places are mapped better than others when using georeferenced images. Places along rivers tend to change over time as the river moves its course. This causes disreprecies between the two maps. In addition, cities with rapid urbanization in the 20th and 21st century would also be harder to map as it would be harder to pinpoint your control points. Examples of this can be seen all across North America as cities have changed dramatically over the past 50 years. However, this means that it might be easier to map from this approach with cities that haven’t experienced urbanization to the extent of other cities, such as Rome. Many of Rome’s key features have been around for centuries allowing the mapping of control points to be much easier than other cities with rapidly developing skylines.

The Calamus Area, Nebraska

Link to original story map: https://uploads.knightlab.com/storymapjs/0237f0ca28f84d79128b33cb2e96708c/gigapixel-placer-county-deep-map/draft.html