Some bands study their influences simply to reproduce their effects, while others strive to learn from them.

Black Mountain's trademark blend of hard rock, prog, psychedelia, and a dash of folk drives their fourth album, insightfully titled IV.

(Well, it's their fourth album if you don't count their soundtrack to the film Year Zero, and they clearly don't.) Black Mountain have long had one foot firmly planted in rock's past, but on IV they don't sound as if they're caught in a loop of nostalgia.

Instead, the band have embraced the stylistic elements of late-'60s and early-'70s smart people's rock, but use them to shape the way they approach the material.

The banks of keyboards, the barking report of the guitar, and the occasional drift into the aural cosmos certainly peg the era of greatest influence for Black Mountain.

But the group's melodies remain fortunately straightforward, even when the arrangements stretch out to invite the spirit (such as on "Over and Over [The Chain]" and Space to Bakersfield").

And despite the group's obvious psych/prog leanings and fondness for stretched-out jams, there isn't a lot of empty virtuosity displayed on IV.

Black Mountain favor texture and drama over instrumental acrobatics, and if the musicians don't aim to impress with their chops, their ideas easily get over on this album.

IV often sounds majestically trippy but rarely noodly, and the clear, full-bodied audio producer Randall Dunn brings to these sessions is a perfect complement for the material.

At their best, Black Mountain approach '70s rock with a 21st century mindset, and that's the sort of sound and feel that make IV so effective.