Mortain
Unfortunately, our first recce in 2002 didn't allow us enough time to visit this crag but we made sure we went there on the latest visit!
There is a short article by Bill Birkett in Climber and Hillwalker for October 1994 (Vol33 No.10)..
From Caen, follow the A84/E401 autoroute WSW to exit 42 (c.21km) then follow the D577 SSW to Vire (c.26km) and the D977 south to Mortain (c24km).
It's also accessible from Domfront - head west on the N176 as for La Fosse Arthour but continue on this road for a further 10km or so to the town of Mortain.
The outcrop lies just north of the town and is signposted as "Le Petit Cascade" from the main road. Park by the Maree and walk a few metres down the hill to the left (facing the Maree) and turn right down a footpath signposted "Petit Cascade". You almost immediately come to a crag on your right - "Les dalles du donjon". 'Les dalles blanches' 4+ / 5a is recommended for a warm up. "pic blanc" is the short pinnacle to the left of the crag.
Further down the path behind some trees is "Secteur Divin Enfant" and further down, the popular "Secteur Babydalle".
We headed down to L'Aguille 100m further on over the bridge. La Gobi was just being vacated so we went for a short walk upstream and round the corner into a gorge. The rock here appears to be less frequented although we did see some ironmongery and some longer lines.
We headed back to l'Aguille and I set off up la Gobi 5+. The rock is quite polished in places and the bolts well spaced but a determined effort gets you going and once you're a couple of bolts up it eases a bit. Further up, you can get right inside the fissure and use a bit of back and footing! Grade wise the 5+ is probably about right although as Bill Birkett suggests, it might well be E1 5a - the 'E' being for effort.
Next, we went back to the Babydalle and mike led off up 'Le Nom de la Rose' 5 - great climbing
...There are at least 75 routes here (reportedly 100 now) in the range 4 to 7 and ranging from 15 to 30m height. The crag is well equipped with bolts and a topo "Escalades sur le Gres Amoricain - Mortain, le site de l'aguille", (published 1991), part of the 'Le Parc Regional Normandie-Maine' trio is available - worth trying the tourist office in Mortain or Domfront or the website here.
La Fissure Gobbi (5+) is recommended by Bill Birkett in the Climber and Hillwalker article.
Websites with further information...
Here with a map and route names/grades
Here more stuff - worldtopo
Here - Club Alpin
I also found an on-line topo for this crag but at present, I can't relocate it - I'll post more here as info becomes available but a search of the web and use of the cosiroc or Rock'n'Orne sites will no doubt point prospective visitors in the right direction.