Academic journal article The Geographical Review

Aquaterra Incognita: Lost Land beneath the Sea

Academic journal article The Geographical Review

Aquaterra Incognita: Lost Land beneath the Sea

Article excerpt

Many times in the past 120,000 years, continental ice sheets advanced (Peltier 1996; Clark and Mix 2002; Carlson and Clark 2012), and the world ocean dropped as low as 125 meters below its current level (Frenzel 1973; Fleming and others 1998; Fleming 2000; Siddall and others 2003; Milne and others 2005; Peltier and Fairbanks 2006; CSIRO 2009). Many times, ice sheets retreated and the ocean rose, once reaching about 5 meters above its current level (Lambeck and Chappell 2001; CSIRO 2009). Thus, there exists a vast earth feature, equivalent to North America in size (Table 1), which transforms back and forth among upland, wetland, and seafloor. The ocean gives and takes like a vast millennial tide--a long-term, irregular cycle--that has persisted for hundreds of thousands of years and continues today (Douglas 1997; Kemp and others 2011; Levitus and others 2012; Moore and others 2013). Spanning much of the continental shelf and a small rim of the world's present coastal lowlands, the feature remains unnamed, though sizable parts of it are named (Beringia, Doggerland, Sundaland, and Sahul), and the submerged portion is mostly unexplored at fine scale. Globally, aquaterra favors the tropics and mid-latitudes (Arctic, 17 percent; northern mid-latitudes, 34 percent; tropics, 38 percent; southern mid-latitudes, 10 percent; Antarctic, 1 percent) and thus clearly would have been the most desirable place for people to live during the ice ages. Knowledge of its existence is owed to a handful of geologists, oceanographers, and other physical scientists who meticulously recorded the evidence of sea level rises and falls and glacial advances and retreats, but the physical and human implications of their discovery hardly have been touched.

Fifteen years ago, I proposed naming this global feature "aquaterra" and urged its exploration (Dobson 1999; Dobson and Dobson 1999). It is the traditional role of geographers to identify, name, define, and formalize earth features, just as biologists do for new plant and animal species. The practice dates from the age of exploration and earlier when new features were added routinely. The first modest step after discovery, then and now, is to give each place a name, as Martin Waldseemuller did when he defined South America as a continent surrounded by ocean and named it America in 1507 (Waldseemuller 1507; Lester 2009). The next stage is detailed exploration, and the final stage is scientific investigation. At present, aquaterra is so poorly understood that it might well be labeled "aquaterra incognita," like "terra incognita" (remote, unknown landmasses) in the early days of terrestrial exploration. Like them, it is ripe for exploration.

In this essay, I further define aquaterra, offer a rationale for its recognition, and suggest an exploration strategy. The name acknowledges its unique character due to the fact that for thousands of years at a stretch it is covered by water (aqua) and for thousands of years it is exposed as land (terra). This name avoids any presentist terminology that would view it as submerged land, rising water, or any other characterization of its present position in the cycle.

Detailed definitions and territorial geographies of aquaterra will facilitate studies of physical and human processes during the Late Pleistocene ice ages. Human migration, for example, can be understood better when the entire "playing field" is known. Human evolution, demic expansions, and the peopling of landmasses can be understood better if all exposed landforms are documented, opening to investigation such issues as sighting distances from island to island (Cavalli-Sforza 1993). Studies of the diffusion of material culture can be greatly improved by better understanding of explicit pathways across aquaterra and advancements within it (Gamble 2013). Island ecology can be understood as a factor in speciation once missing islands are identified.

The greatest justification, however, is the simple fact that so little is known about the seacoast where a significant portion of humankind surely dwelled for the better part of 120,000 years. …

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