Devil's Tower is a basalt tower out west US. It doesn't have sifter rock under the cap, but software rock was around it at one time.

Here is the park site, with photos.

Some mesas that the various tribes in New Mexico live on, don't have soft rocks under the top either.

From Annual Issue 67, a planning template for starships. Width of mapped hull is 840 feet. Height is 600 feet.

Some of my FT3 worlds I created for my Traveller web site: large continent, and an island chain going off into the world ocean.

Some explorers might think there is more land at the end of the island chain, or in this instance, the empty ocean.

They could go around the world, and wind up on the other site of the only continent. The cultures are enough different, the explorers/adventurers think they have found a new land.

The beginnings of Hull 1, the two thin greenish-blue lines are 10' wide corridors with an air lock at each end. The map is 1000' x 800'. That small object is the right most room area is a turbo lift.

Looks like I'll use this scale for generalities, and make smaller maps for each room. Each square of this map is 50'.

I tried using the DD3 passageway tool, and found it easier to work with. Same bitmap fills are available, but I chose Brushed MetalHShuman for this 20' corridor.

My apologies, here is a link direct to the discussion.

This link goes to the forum of Maps and Floorplans.