A volcanic archipelago on the trailing edge of Europa’s outer hemisphere with three primary islands. Stretches in a gentle arc from northeast to southwest; surrounded by the tidelands, which are broader within the arc than outside it. At the far ends of the island chain are several small, uninhabited rocky prominences that are typically above the tideline but become swamped during the highest tiderises. Inhabited by the agrarians.
The southern island is the largest and tallest, and is home to majority of the population. It contains the earliest soil cities, where initial terraforming efforts were centralized, including the southern terminus of the long road. The smaller central island contains a few additional soil cities and is separated from the central island by a narrow channel which becomes traversable at tidefall, facilitating travel between the two islands. The northern island is the smallest and most isolated of the three, separated from the central island by several days of travel, with sheltertown as a midpoint. It was settled much later than the other two and has a shallower soil layer as a result.
Geology
The archipelago is part of a chain of volcanic islands at the seam of two oceanic plates open_in_new , where lava has bled into sweeping hills and plateaus composed primarily of basalt and other igneous rocks. Exposed by Europa’s falling sea level, its rocky islands accumulated a fragile layer of volcanic soil open_in_new blown over in great clouds from its more-active neighbors, augmented by the terraforming efforts of the settlers. It’s islands are capped at their highest elevations by storm-scoured rock and the occasional drift of snow. Their outer edges drop steeply towards the submerged subduction trench open_in_new , while their inner edges slope gently down to the tidelands.
The powerful tides mean that erosion control along the tideline is a critical concern. On the shallower interior coast, erosion control efforts are mostly focused on preserving the finite, precious soil layer. Grasses and other flora that are tolerant of salt spray and exposure to wind and waves effectively bind the soil with their thick, fibrous root systems—and by absorbing water and breaking the impact of droplets, they reduce erosion caused by runoff. On the steeper exterior coast, where the tide has pummeled the volcanic stone into cliffs, erosion concerns are less about the soil and more about the integrity of the underlying stone. While there’s not much that can be done to prevent sudden collapses due to undercuts, regular inspections of the cliffs during tidefall can provide advance notice of instability. In some cases, where the rock is stable enough to withstand the erosion without collapsing, elaborate littoral cave systems open_in_new develop.
Climate
The islands are warm and dry, especially on the leeward slopes. Prevailing winds bring moist air from the ocean, resulting in orographic rainfall——the windward sides of the islands are cooler and wetter. Rainfall filters through the porous volcanic rock, forming underground reservoirs of clean, fresh water. Europa’s geothermal activity presents in the form of plentiful hot springs, geysers, and volcanic vents.
The thinner atmosphere paired with the long days and nights means inhabitants experience a wide range of temperature, with hot afternoons and chilly nights. Although the islands don’t have conventional seasons, they experience weather patterns driven by atmospheric circulation and geography, including irregular periods of volcanic winter caused by nearby eruptions. An occasional moist wind blowing in the opposite direction brings intermittent blooms of life to the arid steppes.
On the leeward side, the highest elevations are primarily steppe, with areas of chaparral biome in sheltered or moist areas of the lower elevations. As the islands slope down towards the inner coast, the grasslands transition to salt marshes, and then finally to the mudflats of the tidelands. On the steeper windward side, XYZ