It’s quite possible that they are volcanoes of different kinds.

The Hereford map of c. 1300 has a multitude of small textured bumps, most of which are labeled with the names of mountains.

https://c8.alamy.com/comp/J4BH80/psalter-map-e-paradise-J4BH80.jpg

I also think that map is the inspiration for the strangely shaped thing that stands in the analogous place to the other volcanoes, it stands where i think the nile would be, except is is pointing to it instead of being its beginning.

https://upload.wikimedia.org/wikipedia/commons/f/fc/Psalter_se_ethiopia.jpg

in fact i think they are all volcanoes of different kinds.

I used to the the one with the crenellations was noahs ark on ararat. But it seems more like mineral. Same as what rains down from the mountain in f84r.

In fact i think it is showing all kinds of minerals. The greenish tint occurs to show the water that comes down off these is not fresh, it will have mineral additives, whether good or bad.

I’m not discounting the possibility that these might be specific tors or volcanoes, rather than fumaroles. I have a long list of possibilities that won’t fit in a blog post.

My point, of course, is to illustrate that there are many possibilities and, until I have enough puzzle pieces to find self-confirmatory evidence within the manuscript, I’m determined to stay open-minded about what they might be.