Just as "roubines" is specific to France, I feel "badlands" is specific to North America.

Michel & Fairbridge propose "terrain raviné" for "badlands", so for "roubines" I would suggest "ravined landform", irrespective of what other translators might have said before. In fact, I'd leave "Roubines Noires" in French and work an explanatory "ravined landforms" into the text somehow – in fact, looking at your text again, there's not even any need to do that!

" Elles forment de grands versants ravinés (roubines noires*) que parfois des plantations d’arbres tentent de stabiliser" – I feel ""Roubines Noires*" should be capitalized, making it clear it is a proper name.

"It (the marl formation) forms expanses of ravined slopes ((known locally as) Roubines Noires*) where trees have sometimes been planted in an attempt prevent further erosion".

Apart from the "black" element, this is neither more nor less instructive to the English reader than the French is to a French reader. You could possibly work in a "of black earth" etc. after "slopes", if/as applicable.

* The formation/area near the Col de Pouriac and Salse Morene in the Parc du Mercantour, in the Alpes Maritimes, actually appears to be called "Roubines Nègres", by the way.

All the above irrespective of the fact that Larousse Lexis, in it's definition of roubine - "(mot prov.). Dialect. Dans le Midi, ensemble de ravinements dans les roches tendres" - states "(syn. BAD LANDS)".
(someone should point out to Larousse that the entry for "BAD-LANDS", a terminological import dating from 1951, is hyphenated).

See North American predominance in
http://en.wikipedia.org/wiki/Badlands

I wonder what the Roubines gnole is. Here twixt Perche and Ouche, the local gnole is calvados of course.


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Note added at 5 hrs (2009-06-05 17:44:16 GMT)
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Liste - Les ROUBINES NEGRES de Salse Morene, depuis le Col de Pouriac. - Vignettes (août 2002)
www.lemercantour.com/RoubNegres.htm

Les ROUBINES NEGRES • Regard en arrière vers le col des Fourches • La cîme du Mul • Pause au Lac • Au col de Pouriac, l'Italie ...
www.skipass.com/blogs/maniac/la-tete-de-l-enchastraye.html

Le fait que dans la Haute Provence le mot roubine désigne "roche schisteuse" pose un problème, mais j'ai trouvé quelques images des ROUBINES-NEGRES qui ...
etymologie-occitane.chez-alice.fr/R.html

alpages verdoyants du Salso-Moreno supérieur dominés à gauche par les ravinements noirâtres des ROUBINES-NEGRES. Le sentier descend très ...
www.arsac.org/wihem/blog/blog/Paca/2009/03/06

Alpage entouré des ROUBINES NEGRES, du Pas de la Cavale et du col de Pouriac (Hameau du Pra). La lumière matinale souligne l'impression de liberté, ...
www.routard.com/photos/provence/10136-alpage_du_salso_moren...

Ou ces ROUBINES NEGRES, étranges saignées noires qui descendent jusque dans la prairie. Il y a ces marmottes, qui courrent de partout, alors que nos ...
aventuralpines.over-blog.com/article-6783408.html

Pas besoin de préciser pourquoi on appelle ce coin les ROUBINES NEGRES : http://img444.imageshack.us/img444/5007/rpbonette229bordernm... ...
www.randonner-leger.org/forum/viewtopic.php?id=7285

Découverte du cirque du Salso Moreno, caractérisé par sa barre de ROUBINES NEGRES. Belle montée sur de la pelouse alpine (attention les marmottes ! ...
philippecoumont.free.fr/spip/article.php?id_article=2

55 ghits for "Roubines Nègres", 4 for "Roubines Noires" (of which 2 are on ProZ)


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Note added at 6 days (2009-06-11 16:11:38 GMT) Post-grading
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Just as long as it's not a soggy one, I accept.