Noteworthy exceptions aside, Colorado bluegrass is ordinarily associated with the infusion of pop elements along with instrumental experimentation. As a general principle it is not to my taste. I am not a hidebound traditionalist -- mouldy fig, if you want to be particularly uncharitable about it -- in these matters. Or at least I hope I'm not. I do, however, like some drive in my 'grass and a touch of mountain air. A band with Colorado in its name is bound to raise the eyebrows of bluegrass buffs of my orientation, not to mention expectations of a soft-core sound.

If that's what you happen to be looking for, though, it isn't here. Jeff Scroggins & Colorado traffic in the hard stuff, and nobody can doubt their commitment to the tradition Bill Monroe and the other foundational figures fashioned in the middle of the last century. Even so, they don't come across as in any way generic or imitative. This is the tradition on their terms, with some unusual material, by which I don't mean 1950s country obscurities but cuts written by artists one doesn't associate with bluegrass-friendly compositions: Willie Nelson, the late Dennis Linde (best known as the writer of the 1972 Elvis hit "Burning Love"), Jimmy Webb and Gordon Lightfoot.

True, Reno & Smiley's "Wall Around Your Heart," Leon Jackson's "Love Please Come Home" and Hylo Brown's "Down the Road of Life" are straight out of the Bluegrass Songbook, though fortunately not its most turned-to pages. These are songs eminently worth reviving, with lead vocals by Greg Blake (whose solo disc, Songs of Heart & Home, I reviewed happily in this space on 5 March 2016). Blake handles every style of song here without ever seeming to break a sweat, though some feel as if they might have been a bit tricky to pull off (e.g., David Keenan's left-field "Sometimes Dig for Taters") in a less supple throat.

Probably, at some point a bluegrass outfit has covered Webb's "Galveston," made hugely popular by country-pop artist Glen Campbell (with a swelling string section) in 1969, but I don't recall hearing it if it exists. Scroggins & Colorado's arrangement gives it, improbably, the aura of a genre natural. "Carefree Highway," among the many exceptional songs Lightfoot wrote in his prime, soars.

An able and inventive banjo picker, Scroggins doesn't sing himself, but his playing moves along with conviction, taste and nuance. His son Tristan offers up some melodic mandolin. Bluegrass notables Andy Leftwich (fiddle) and Mark Schatz (bass) are welcome wherever they land. Don Rigsby and David Peterson, who record (separately) under their own names as deeply traditional 'grassers, provide harmony vocals. Joy and glorious music abound.