The Silvan Basin is a vast polar depression on planet Verthandi, created by an asteroid impact many thousands of years before human colonization. The Silvan Basin is thousands of kilometers across and is large enough to encompass the Azure Sea, the Fox Island plantation, and enormous tracts of blue-green jungle. The Basin Rim cliffs that form the perimeter of the Basin are the eroded remains of the ancient crater's edge. There are numerous logging trails and roads throughout the area.
- Mercenary's Star, p. 114, "Gunnar Ericksson describes local geography to Grayson Carlyle"
- Mercenary's Star, p. VI, "Verthandi surface map details"
- Mercenary's Star, p. 37, "Devic Erudin mentions lumber businesses within the Silvan Basin"
- Mercenary's Star (Novel)