Mark S. Monmonier. Coast Lines: How Mapmakers Frame the World and Chart Environmental Change. Chicago: University of Chicago Press, 2008. xiii + 228 pp. $25.00 (cloth), ISBN 978-0-226-53403-9.
Reviewed by Sally Hermansen (University of British Columbia)
Published on H-HistGeog (September, 2009)
Commissioned by Arn M. Keeling (Memorial University of Newfoundland)
Variations on Drawing the (Coast)line in the Sand
How does a cartographer, or chart maker, draw a line in the sand/on the map demarcating a coastline? What about tides, storm surges, and sea level rise? Is the coastline high tide or low tide, or somewhere in between? How do engineers know how high to build dikes to safeguard against storm surges? How should coastlines be altered for sea level rise in current planning for future coastal communities? How have coastlines been dealt with historically? What is scientific and what is socially constructed in the cartographic representation of coastlines?
These are some of the intriguing questions that Mark S. Monmonier asks, answers, and gets one thinking about in his latest book Coastlines. A Distinguished Professor of geography at the Maxwell School of Citizenship and Public Affairs at Syracuse University, Monmonier is a prolific author on topics concerning cartography and society, and has provided a great deal of guidance in the interpretation of information displayed on maps. Most of his books cater to both academic and public audiences--perhaps his most noteworthy being How to Lie with Maps (2d. ed., 1996). He is also currently editor of volume 6 of the History of Cartography series. Coastlines is no exception to what we have come to expect from this exceptional scholar: well researched and referenced, captivating and engaging, with detailed stories set in a broader context of understanding, and a balance between scholarly thought and nontechnical writing for a public audience. His books are simply a delight to read. Readers are introduced to Coastlines in chapter 1 (“Depiction and Measurement”) and chapter 2 (“Definitions and Delineations”), which introduce four categories of coastlines: the high water line, the low water line, storm surge lines, and sea level rise lines. The first two have an interesting history of representation over time, and are more complicated in their calculation than they appear, given variations within high and low water lines and variations between oceans and countries. The last two lines reflect more recent coastline issues with which cartographers are grappling as the increased frequency and intensity of storms, such as those common in the Gulf of Mexico, flood coastal communities (storm surge lines) and as global warming/sea level rise scenarios are proposed that depict current coastal cities under water (sea level rise lines). Included in this initial discussion are terms and definitions relevant to understanding the portrayal of coastlines, particularly the implications of scale, generalization, and resolution.
Chapter 3 (“New Worlds and Fictitious Islands”) presents some pre-chronometer historical coastline anecdotes, such as California as an island, leading into chapter 4 (“Triangles and Topography”) and a discussion of the increasing accuracy of triangulation and topographic surveying in the nineteenth century. Chapter 5 (“Overhead Imaging”) describes current satellite and airborne imagery that yields precise, accurate imagery taken at frequent time intervals and data on those lines in the sand, while chapter 6 (“Electronic Charts and Precise Positioning”) provides a review of electronic charts and position information used today in ships, including an explanation of map projections (an understanding that is vital to positioning).
The political and international considerations of coastlines are discussed in chapter 7 (“Global Shorelines”) and chapter 8 (“Baselines and Offshore Borders”). While it took almost one hundred years for an International Map of the World to be commissioned (1891) and then abandoned (1987), a General Bathymetric Chart of the Oceans (GEBCO), initiated by Prince Albert I of Monaco in 1903, was more successful, both in its initiation of the still-functioning International Hydrographic Association (IHO) and in a number of editions of the coastline map sheets covering the world. But what datum was used and how were tides considered? The first GEBCO was at a scale of 1:10,000,000 (at least that is the scale at the equator--the distortion of the Mercator map projection of this series generates much larger scales toward the poles) and an appropriate level of generalization. But given the fact that a thin line is the equivalent of a corridor more than three miles wide, does it really matter if the high water mark, low water mark, or something in between was used? These discussions should lead us not only to think about the use of these world coastline maps, but also to question current digital data (such as the Digital Chart of the World, or DCW) and its history, generation, reliability, and accuracy (especially since digital databases tend to be scale independent in their use). The highly generalized coastlines of world databases are problematic for the delineation of coastal sovereignty of nautical waters, especially those waters that provide habitat for commercial fish and cover offshore oil deposits. In these cases, tiny islands, even sandbanks and jutting coastlines otherwise generalized at smaller scales, are critical in determining economic and sovereign zones. Monmonier documents through text and maps many fascinating examples of the trials and tribulations of the demarcation of these zones, such as the maritime boundary between Canada and the United States in the Gulf of Maine--complicated by Nantucket and Cape Cod--that was ultimately resolved by an international court in 1854.
Chapter 9 (“Calibrating Catastrophe”) discusses the third type of coastline: storm surge lines or one-hundred-year flood lines--lines crucial for flood insurance, but also a perfect example of the social construction of cartographic data. Included in the discussion is an explanation of the data (including historical storm data) and numerical modeling used to simulate these surges and the resultant impacts on coastal basins and ripple effects. In turn, the author shows how these data are translated into projected flood lines on maps. Again, through these explanations, supported by visual examples, readers are asked to question the accuracy of the lines, and the social construction behind the generation of these lines for insurance and risk purposes.
Chapter 10 (“Rising Seas, Eroding Surge”) takes us to the last of the coastlines, predicted sea level rise lines as a result of global warming. While we may think of this as a recent (that is, the last ten years) coastline phenomenon, in fact, tide gages have been recording variants in sea level rise for over one hundred years and their impacts not only on human settlements but also on marshlands and beach profiles. These tentative coastlines (the example given is the shrinking of Florida and ice sheets melting) make very powerful maps in soliciting public and government support on the question of global warming.
The final chapter, “Close-up and Complexity,” provides detailed examples of the depiction of coastlines on historic and present-day Internet maps, while an epilogue summarizes the four categories of coastlines. Although the subtitle of the book How Mapmakers Frame the World and Chart Environmental Change, and the inside leaf describing the book (which discusses only sea level rise), may be misleading (only two of eleven chapters are devoted to this specific topic), Coastlines provides historical geographers, environmental historians, and historians of science with extremely engaging insights on the demarcation of coastlines.
If there is additional discussion of this review, you may access it through the network, at: https://networks.h-net.org/h-histgeog.
Sally Hermansen. Review of Monmonier, Mark S., Coast Lines: How Mapmakers Frame the World and Chart Environmental Change.
H-HistGeog, H-Net Reviews.
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