Not a "dome" just the illusion of one.

It looks like ancient Russian earth mounds, some are pretty big, I think they are called Kurgans and are burial mounds of stones and raised earth. BTW, did you mean your pictures to be live links to imageshack?

Looking again, I think this is actually a permanent 'Pingo' It is near the port of Tiski, and that is an area that is permafrost. The Pingo is an uplifting of earth and ice caused by upwelling liquid water from below that then freezes.
The contour lines around the dome is characteristic in a large Pingo. the other circles are likely pingos as well.








This snow covered example is from Canada.

Can the original poster use Google Earth rather than maps, then post the coordinates?

Often if there is something interesting, a google earth community marker is place there. Of course, the community is often wrong. ;-) But the marker has an associated thread which often corrects the initial data.

Originally posted by gariac
Can the original poster use Google Earth rather than maps, then post the coordinates?

Often if there is something interesting, a google earth community marker is place there. Of course, the community is often wrong. ;-) But the marker has an associated thread which often corrects the initial data.

The area is Tiksi port/bay, Sakha Republic, Northern Russia LAT: 71°44'40.81"N
LOG: 129°24'19.41"E

Thanks to you all salt mines sound plausible
Thanks for your efforts...