Another spell from an old 4e spell list and rewritten for Ars Magica 5th edition called the “Builder of Mountains“.
Raise the Spine of the Earth
Creo Terram 60, R: Touch, D: Momentary, T: Individual, Ritual.
Once complete this ritual spell causes a towering mountain range to gradually rise from the earth, growing to full height over the course of a day.
The mountain of rock grows as a steep rough ridge between two offset conical peaks, to a full height of over 20,000 feet high and 9 miles wide at the base. The caster can dictate simplistic patterns, shapes, and insets within the overall shape and orientation.
All structures and formations caught in the path of the growing mountain will be destroyed or severely damaged, only the position of the caster at the very peak is relatively safe. Most small plants will survive unharmed, however larger plants may well be uprooted or subsumed by the mass of earth and rock.
(Base 3, +1 Touch, +11 Size, +1 Intricacy)
The base of 1 cubic pace for stone is expanded up to approximately 15 cubic miles of material, which is more than enough to raise a monolithic and steep mountain into a region.
The Iron-Bound Tome 
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I can see this for a Transforming Mythic Europe-esque/ Hermetic Projects style game (in fact it works well with the Burning City, and Great Tower chapters of Projects and the Island of the Magicians chapter of TME)
The defunct pbp forum game Atlantis had a similar spell which raised a underwater ridge into a mountain range – I couldn’t find the SG’s version of that spell to ref, but that’s what always came to mind. It’s a huge spell, but Ithink an epic game might find a major story beat / world event in the casting of something like this by the player characters.