Yes, marl is a Scrabble word!
...and is worth 6 points in Scrabble, and 8 points in Words with Friends
marl
Noun
1. A loose and crumbling earthy deposit consisting mainly of calcite or dolomite; used as a fertilizer for soils deficient in lime
What Scrabble words can I make with the letters in marl?
3 Letter Words
2 Letter Words