The kids of today have no idea what they missed out on.

They know this band called Alice in Chains, but with a lead singer named William DuVall. Please, somebody -- anybody -- teach America’s youth about the glory days of Alice in Chains. You know, when Layne Staley was lead singer. The first lesson should be this record, which today turns 21.

Some Alice fans might start the kids with the band’s 1990 debut, ‘Facelift,' which features that echo-chamber distortion-time-bomb ‘Man in the Box,’ and then have them work forward. But the group's second album is their genius moment -- their true tour de force.

Two things set Alice in Chains apart from the day's various grunge bands du jour. First, their sound was much more steeped in the traditions of metal and that genre’s guitar heroes -- bands like Black Sabbath/Ozzy Osbourne, Slayer (bassist/lead singer Tom Araya appears on ‘Dirt,’ however briefly) and Metallica. (Grunge has its roots not just in metal, but in punk and garage rock.) So when revisionist music historians refer to Alice as "grunge," it’s a misnomer. To wit, at the time they broke, they were placed on tours with legacy metal acts like Anthrax, Slayer, Van Halen and Megadeth.

Second, the band had a pair of lead vocalists in singer/lead guitarist Jerry Cantrell and Staley, and their melody-harmony interplay was way more inventive and sonically charged than that of their contemporaries. Sure, Nirvana had Kurt Cobain’s highly distinctive, ragged pipes peppered with spot-on high-harmonies by drummer Dave Grohl (‘Nevermind’ had been out for a year at the time of ‘Dirt’’s release); but neither Cobain nor Grohl had the sheer low-high range or natural vibrato of Staley and Cantrell, and together, they lacked the otherworldly connective tissue.

In turn, Pearl Jam, whose ‘Ten’ sat on the charts when ‘Dirt’ dropped, had just one distinctive-sounding lead singer and a twin-guitar attack. Eddie Vedder was more of a high-range howler than a singer, and Mike McCready and Stone Gossard sound like really good Guitar Center noodlers compared to Jerry Cantrell and his monster metal chops.

Listening to ‘Dirt’ today, there are two things to note. It was one of the first albums that made it OK for metalheads and grungers to mosh in the same pit, and it was a way darker statement than anything on the radio at the time, as it's chock-full of drug references and ghoulish riffage. Second, it doesn't sound like anything released at that time, and today, it lacks the dated ’90s production both ‘Nevermind’ and ‘Ten’ suffer from.

In short, 'Dirt' is timeless.