A Belgian holiday

 This picks up from A Roman Holiday about aspects of Roman Roads. A friend pointed out this YouTube video, How A Roman Road Changed Belgium Forever, here is their synopsis:

Why does Belgium speak two languages? The answer is a 2,000-year-old Roman road.

In this video, I explain how the Via Belgica, a highway built by the Roman empire around 50 BC, created a language border that still divides Belgium today. The road ran from Tongeren to Bavay, separating Romanized Gaul in the south from Germanic tribes in the north. That linguistic divide has persisted through the Middle Ages, Spanish rule, Austrian rule, French occupation, and Belgian independence.

Today, Dutch speakers live north of the line, French speakers live south of it, and the border is still influenced by that ancient Roman road. Even Belgium's election results are decided by this 2,000-year-old line.

Having mapped Roman Roads, I recreated a focussed map on the region, adding the Belgian Wallonie region in green. As roads were unidentified in the AWNC database, I selected them per video. I found a source (no metadata in arcgis.com) that put Via Belgica right along it, confirming my choice.

click to enlarge, full size

Notice how Roman Via Belgica lies along the N edge of present-date Wallonie. Note also larger the extent of the sea water encroaching in "archaic" (light blue), "medium" (pink) & Roman ("open" tan) times. Current river courses also tan to match the sea. Indirect evidence, less settlements N of Via Belgica. Note also how the Roman Road web overlays by-and-large current cities. 

Note: for those in East Anglia, notice at top left near Norwich, the Norfolk Broads are entirely under sea!

Perplexity AI comparison of current vs. mapped stats are Sheet 1 here and summarize by me as:

Derived estimates	Roman period (Via Belgica corridor)	Modern period (same rectangle on map)
density settlements	0.5 / squ. km.	exceed 1 / squ. km.
density population	tens / squ. km.	350 / squ. km.

While the population density difference isn't surprising, the settlement density difference is - only half the present, when population density is an order of  magnitude smaller - you can see their spread as black dots on the map.

Much to my amazement, Perplexity was able to distinguish between sides of Via Belgica! Details are Sheet 2 here and summarized by me as:

Relative to Via Belgica	Roman	Modern
North / West	Low density, marshes, small rural settlements, widely spaced	v. hi dens., near-continuous, major ports & cities, kms. spaced
South / East	mod. density, provincial capitals, villas, forts, mod. spaced	hi-v. hi density, urban-industrial corridors, 10s km. spaced

3D maps in current affairs

 This pics up on the previous Beautiful maps... as well as Arctic Waterfront... re: the distribution of influence over the Arctic in the news of late.

This time let's look at the elevation maps of the area:

• High Resolution Elevation Model of the Arctic (Esri Living Atlas)
• Seabed Sediment Thickness (Esri Living Atlas)

Arctic DEM in tan-green & sediment thickness in blue-cyan (click to enlarge, full size)

The sediment thickness acts as a proxy for basement depth: if seabed is relatively uniform as in a closed ocean like the Arctic (without continental shelf & abyssal plain) then the thickness is roughly equivalent to the depth to basement. So it acts as on offshore extent of the detailed relief map, highlighting where the ridges are in particular: this is important as Russia laid claim to the North Pole as the Lomonosov Ridge underlying it extends into Russian waters (Am. Soc. Int'l Law).

Let's now add sea ice extent and shipping lanes. Climate warming is opening up both Northwest Passage & Northern Sea Route (Perplexity), respectivley West across the Canadian Arctic Islands and East over Siberia to China. The former may still be problematic with relatively narrow channels. But the latter is a boon for China to, say, ship EV's (electric vehicles) to Europe & America... thus avoiding the troublesome Red Sea & Suez Canal or the distant southern tip of Africa!

• Median Sea Ice Extent for the Arctic (Esri Living Atlas)
• Shipping & Hydrography (NGA Arctic Summit, Esri News)

Sea Ice Extent & Shipping (click to enlarge, full size)

In this "International Space Station view", the Northwest Passage is in black, the Transpolar Route in green & the Northern Sea Route in red. Notice the bald spot atop? Although the Esri Living Atlas from this month explains the provenance details, "atmospheric physicists find error in widely cited Arctic snow cover observations" (physics.org). We're only interested, however, in the southern edge that affects shipping lane: six years ago I mapped the sea-ice extents; web- & story-maps in the linked blog post are gone (viz. indented paragraph here), but I posted a video here:

blog: Community, Climate and Maps...

In fact I created this to bird-dog NOAA vs. NSIDC data six years ago here, when I thought they underestimated the ice shrinkage and the impact on climate change & sea level rise.

Follow the rest of my Arctic coverage here, and share in comments below your questions & stories.

Arctic Waterfront, a measure of geopolitical stakes

 Update: next in the series on the Arctic is here with more data & a 3D view.

A mid-2011 post Beautiful maps in current affairs (note the updates) said: 

UN Convention on the Law of the Sea [...] by Dr Parson of the Southampton UK National Oceanographic Centre [...] described how nations were given an opportunity to claim Exclusive Economic Zones (EEZ) beyond the standard 200 nautical mile limit (viz. UNCLOS and UNEP). [...]