Vadological Wadden Sea

Jacob Shell

Looking through the Wadden Sea quadrangles of a beautiful German topographic series from the 1890s (the Reichsamp für Landesaufnahme series), I’ve focused on three peculiar marked features, all similar yet symbolized and labeled somewhat differently. These features raise questions pertaining to cartography, as well as to human methods of living with and moving across transient and floodable landscapes.

But first, the general location of the Wadden Sea, for readers unfamiliar with it. It’s a broad intertidal zone along the North Sea coast of continental Europe, including Danish, German, and Dutch areas:

Dark blue is the Wadden Sea intertidal zone.


Turning to the 1890s topo series (link to the full series, which covers all of the Second Reich German Empire, at bottom of this page), I am interested in details from three quadrangles:

In the quadrangle for the environs of Duhnen village and the island of Neuwerk (at the mouth of the Elbe River), linear chains of Y-like symbols criss-cross the mudflats of the Wadden Sea’s broad intertidal zone. Only one of these chains of Y-symbols, the chain connecting the mainland village of Duhnen with Neuwerk Island, gets a label: “Wagen-Weg (bei Niedrig-Wasser)” [Wagon Way (at Low Water)]. See map detail below:

Duhnen-Neuwerk (central Wadden Sea) detail of 1890s Reichsamp für Landesaufnahme topo series.

In the quadrangle for the environs of Norderney Island in the Wadden Sea’s West Frisian Islands, a dotted double-line crosses the flats; the line is labeled “Post-Weg” [Postal Way]. (“Frisian” refers to the main linguistic and cultural group historically associated with the Wadden Sea). Note that this corridor crosses a chain of Ys. See map detail below:

Nordeney (West Frisian Wadden Sea) detail of 1890s Reichsamp für Landesaufnahme topo series.

Finally, in the quadrangle for the environs of Amrun and Fohr Islands in the Wadden Sea’s North Frisian Islands, a dotted single-line crosses the tidal mudflats and links the two islands; this line is marked “Verbindungsroeg wahrend der Ebbe” [Connector-path during Low Tide]. This line crosses a chain of Ys as well. See map detail below.

Amrum-Fohr (North Frisian Wadden Sea) detail of 1890s Reichsamp für Landesaufnahme topo series.

All three are attempts at making cartographic sense of the unconventional methods of facilitating transport across the vast intertidal landscape of the Wadden Sea. The so-called Wagen-Weg between Duhnen and Neuwerk Island was, and still is, for convoys of fording horses who pull amphibious carts. This fording horse-cart system persists in the 21st century as a primary mode of access to Neuwerk, which contains a historically important lighthouse for ships entering and exiting the mouth of the Elbe, a river course which leads to the port of Hamburg (see the two images below).

Transport to Neuwerk Island (Jürgen Benner)

Transport to Neuwerk Island (Reese-Winne)

The Y-like symbols on the Neuwerk map detail refer to “pricken”: cut tree branches pierced into the mudflats to make the proper path across the flats visible when the tide comes in and covers over the mud (see the image below). On the map, or at least the Neuwerk quadrangle of the map series, there appears to be a distinction between the Y-symbol chain marked as the Wagen-Weg, and the Y-symbol chains marked with no label: the former being for fording horses and human waders headed to Neuwerk; the latter being for boats’ attempting to follow the flats’ low-tide water channels, signaling to those boats the presence of underwater mudflats and shoals they won’t be able to see. The way the map “flattens” these two modes of movement, wading and boating, with their apparently distinct challenges vis-à-vis the elements and the tides, is intriguing, even if in many ways counterintuitive and confusing. On the other two quadrangles, the Y-symbols refer only to low-tide boat navigations.

Pricken near the town of Wremen (Anatole Danto)

Note the prickens’ flexibility: they can be lifted and re-pierced into the mud, or new sticks fetched, as the landscape’s configuration of sands and tidal channels shifts with the passage of time.
(Another note: the challenge of boat-navigating these mudflats’ emptying channels as the tide ebbs provides suspense for several chapters in Erskine Childress’s 1903 spy novel, “The Riddle of Sands,” which is about a German plot to invade Britain using a secret armada hidden in the Wadden Sea).

The “Post-Weg” and "Verbindungsroeg” of the other two maps both refer to horse-based fording paths ("roeg" appears to be a local term meaning road or pathway). Unlike the fording-way to Neuwerk, these two fording-ways no longer exist in 2020. A historical photo of Norderney Island’s mudflat-fording horses is below. I have not found a historical image of historical mudflat-forders between Amrun and Fohr, but evidently the path was important enough to merit visualization on the 1890s topo map series (though with the single-line, not double-line—possibly indicating lesser importance). The inconsistency in labeling, categorization, and symbolization of these trans-Wadden fording paths is telling: these patterns of movement are themselves constantly shifting, and do not entirely lend themselves to the sort of geovisualization generally preferred by cartographers, whose overriding impulse can be to simplify geography into fixed linear distinctions, such as between “land” and “water,” or between “road” and “not road.”

Hinrich Dinkla, Norderney, 1930 (Bild: Familie Diepen)


This wading- or fording-based method of island connection is an example of what I’ve elsewhere called “vadology” or “vadological” transportation—from the Latin “vadum”, meaning a wading or fording spot, or a water shallows. (See discussion here:
This style of transportation, today unusual though perhaps with durable value, has been especially important in the Wadden Sea, historically and to some extent in the present. This is because the Wadden Sea’s large low-tide mudflat zone creates daily problems for the mobility of floating vessels. Building permanent causeways above the high-tide water line or dredging permanent low-tide canals offer two conventionally “infrastructural” methods of facilitating access to the islands, across (or in spite of) these mudflats—indeed, many islands in the Wadden Sea are reached this way, by causeway or by low-tide dredged canal. However, many of the Wadden Sea’s islands are too small to justify the economic expense and ecological damage such permanent infrastructural works require. By contrast, transportation methods organized around the systematized practice of wading and fording—that is, organized around vadological movement—can flexibly adapt to different stages of the Wadden Sea’s tidal cycle, as well as to the region’s dynamic geography of constantly shifting sandbars and meandering tidal waterways.

The name of the Wadden Sea is itself etymologically related to the neologism, vadology. The Low German Wadden, the Latin vadum, and the English “wade” all share common Indo-European etymology. Horses are not the only quadruped around the Wadden Sea to help facilitate vadological transport. Dog-drawn mudsleds are traditional, and occasionally still used, in the Wadden flats around the town of Wremen (see below). Vadology is also conceptually central for understanding why Asian elephants have persisted as a means of monsoon-time transportation in northern Burma (Myanmar) and eastern Arunachal Pradesh, where I did fieldwork on the subject of elephant-based human mobility during the 2010s.

Erhard Djuren's dog mudsled near Wremen, c. 2010 (photographer unknown)

Erhard Djuren's dog mudsled near Wremen, c. 2010 (photographer unknown)


Shoreline transience has been a constant theme in the history and present of the Wadden Sea. A remarkable German map from the 17th century, below, shows the dramatic changes in the geography of the North Frisian Islands in the year 1240 vs. the year 1651 (evidently the 17th century cartographer had access to geographic information from the medieval period, though we should assume this info is somewhat inaccurate). Many of these changes were caused by the Burchardi Flood of 1634, which eliminated the island of Strand and replaced it with smaller islands such as Pellworm and Nordstrand.

Johannes Mejer, 1651 (with 1240 conjecture on right)

More so than the West Frisian Wadden Sea, or than (southwest of this) the Dutch Wadden Sea, the North Frisian Islands region of the Wadden are characterized by a unique hierarchy of dike types. Some are enormous dikes designed to protect either the outer islands or the Schleswig-Holstein inland from bad storm surges from the North Sea. However, others are much smaller, and protect smaller, partially human-built islands internal to the Wadden Sea’s intertidal. These smaller levees and islands are locally called “Halligen,” and usually contain just a handful of houses, surrounded by smalls farms and meadows (usually for sheep). The time and shared social investment which goes into building the Halligen suggest that these smaller islands are, to some extent, intended as permanent. And yet, the limit placed on the Hallig dike size also implies a degree of flexibility: an acceptance that the day may come when a Hallig must be abandoned and a new one built elsewhere in the Wadden Sea’s evolving littoral geography. (Today, many of the Halligen are becoming abandoned because younger Frisian-Germans are leaving this way of life due to its apparent isolation compared with life in, say, nearby Hamburg).

Südfall Hallig

A painting from 1911, Erik Kohl’s “Old West Tower in the Surf,” dramatizes the Wadden Sea’s characteristic transience (see below). The Old West Tower, actually the second of three towers at or near this site, was built circa 1600 as a lookout for the West Frisian island of Wangerooge. Coastline erosion during the next three centuries caused Wangerooge’s coastline to retreat eastward, so that by Kohl’s day the tower was its own island, off the coast, as portrayed by the artist Kohl. A third tower was built in the early 1930s in the interior of the island, and today there is hardly a trace of the old tower, besides some underwater foundations.

Erik Kohl, “Old West Tower in the Surf”, 1911