I couldn't find much more than the official overlight Kickstarter preview pdf.
The Preview is silent on absolute sizes
The best extrapolations from the preview PDF are the absolute minimum sizes for two shards based on their short characteristic. These range from "40 km Diameter/280 square miles" over "4400 square miles at absolute minimum" to "around 200,000 square miles as minimum". These sizes would dictate the size of Haark, as Haark has to be the largest.
If the description of "continents floating" is read as "tectonic plate", then it would be safe to take an absolute minimum of 250,000 square miles for the size of Veile. Remember though, that the average minor tectonic plate is between one and two magnitudes larger.
The lower bounds of proper continents start between Greenland and Australia. A ballpark number of 2.5 to 25 million square miles would allow offering the vast expanses demanded by some shards, but it collides with the description of Haark as one monolithic city.
Nova: Rocky towers and crumbling mesas dot a
horizon of sandblasted expanses, shimmering
and brilliant white in the neverending light. p11
a Horizon of sandblasted expanses means, that a typical person standing at some sort of "average level" can't see the edge of the floating shard. Assuming that the curvature of a shard is somewhat in the area of the earth, then this gives us a lower limit for Nova, but no upper limit - 4.7 km radius minimum if the average level is "sea level" and a ballpark of 19.6 km if he stands on a 30 meter tall rocky pillar. But that is just a rough minimum, that doesn't help a lot, as this minimum 20 km radius circle would only cover an area as big as the area inside the Capital Beltway in Washington DC (~280 square miles) and then you'd have to stand exactly in the middle to get this one described view.
Zenith: Towering mountain ranges
This is all we learn about the landscape. The best we can say is expansive.
Quill: The jungles and torrential rivers of
the floating islands of Quill [...]
Once they were emperors of their domain, with
sprawling cities of spires [...] Teryxians cling to the remnants of a ruined
civilization while they try to avoid becoming
prey to the appetites of the junglep11
The plural indicates that Quill is rather expansive with large distances between the cities, but no clear indication about how large these cities are or how distant. It doesn't solve our problems though.
Banyan: Each tribe upon
this forested shard is inextricably linked to
their unique Hearthwood Tree, [...]. These
monumental wooden behemoths [...]p11-12
Sadly, monumental wooden behemoth is not defined, but considering the average distance between large trees - for example in redwood forests or in the rainforest - this implies a rather large landmass.
Haark: A single magnificent city, covering
almost the entirety of the largest of the shards. p12
This is the best information we get about the size: this is the largest shard and it is one city. A few comparisons about the size of metropolitan areas I found: The Île de France, which is pretty much the Paris Metropolitan area, has 4,640 square miles and a population of 12 million people. The New York Metropolitan area is 8,683 square miles and packs 17.8 million, Tokyo does 33.2 Million on a 6,993 square miles area.
Veile: The idyllic hills and estates of Veile
overlook placid lagoons and inland seas.p12
Inland sea implies that is is clearly not a lake. When is a sea a sea? on Earth, the 5 smallest seas are:
- the minuscule Sea of Marmara with 4,400 square miles
- the Sea of Cortez with 62,000 square miles
- Persian Gulf with 97,000 square miles
- Baltic Sea with 146,000 square miles
- Yellow Sea with 150,000 square miles
That gives us a minimum estimate of some 6,000 to 200,000 square miles, but no upper limit.
Pyre: Often bathed in darkness, the tundras and
steppes of Pyre are lit by the glow of the shard’s
volcanic mountain ranges, which frequently
result in rivers of magma coursing through the
Again, no indication but that there is enough space to feature two vastly different biomes, which speaks of quite an expanse, but we can't put numbers on it.
As I was spurred, I grabbed the chapter 6 preview, and could squeeze out a few more information. For example, the day-night-cycle holds this info:
the slow movements of continent-sized
Well, this isn't much, but what is the smallest continent - or, as we speak about floating landmasses that carry water, what is the smallest tectonic plate?
The ring of fire is a tectonic zone around the Pacific, and it contains a Microplate called Juan de Fuca Plate. This one is responsible for a lot of earthquakes between Canada and California. It's "just" 250,000 square miles large, fitting the upper-minimum bounds we found in Veile by taking the smallest seas. The next ones are just a random pick from the list but should illustrate about what counts as a proper tectonic plate.
The South Hebrides Plate as well as the Burma Plate come up to about 1,100,000 square miles and are the smallest, the Cocos Plate is 2,900,000 square miles, the Caribbean Plate comes up to 3,300,000 square miles, the Arabian Plate is 5,000,000 square miles, and the biggest minor plate is the Somali Plate with 16,700,000 square miles.
If we read it more literally, then the smallest continent is Australia, 2,900,000 square miles and about as large as the Cocos Plates. Greenland also is in that ballpark with 2,100,000 square miles.
This gives us a somewhat different ballpark of the size that should/could be aimed for: 1 to 2 magnitudes more than from the descriptions minimum sizes might be intended, maybe even more.