Few subdivisions of heavy metal have been more shrouded in obscurity than sludge metal. Mainly rooted in hardcore punk ferocity and Black Sabbath-esque misery, sludge metal’s perpetual isolation allowed it to grow into a multifaceted movement influenced by multiple genres. In spite of how many directions it has gone in as it evolved, hideous thickness and unadulterated hatred have remained cornerstones of its sound. The following albums are meant to hurt your feelings, but also provide a great entrance into the floodgates of sonic decadence.

Melvins

“Houdini:” These Washingtonian madmen have unabashedly crossed genre boundaries over their extensive career, influencing everything from Seattle grunge to the OC garage rock revival. However, their place in sludge metal cannot be denied. Melvins’ “Houdini” is an early example of the synthesis of ‘80s hardcore and ‘70s proto-metal that foundationally defines this movement. Plenty of arguments could be made against “Houdini” being a pure sludge metal album — several songs on “Houdini” noticeably divert from what would be considered sludge or even music in the traditional sense. Yet, the bands below owe their existence to what Melvins accomplished early on. Even by today’s standards, the weightiness of their music remains inexorable.

Crowbar

“Odd Fellows Rest:” Although many bands could be argued as the quintessential sludge band, Crowbar stands as a prime example of the fully developed genre. Crowbar sticks to their punishingly danceable form without becoming boring in the least. Seriously, these songs are all perfect. Juxtaposing groove only New Orleans could produce with unbelievably catchy riffage and plodding rage, this record’s obliterative riffs and painfully soulful vocals guide the listener through corridors of Southern malice. “Odd Fellows Rest” sparingly accentuates punk rock elements, allowing it to subtly propel the music rather than clash with its gloomy backbone aspects. Although oppressively crushing throughout its runtime, “Odd Fellows Rest” maintains undeniable songwriting chops that harken back to more friendly types of music.

Iron Monkey

“Iron Monkey:” Iron Monkey pole vaults far beyond where the likes of Crowbar planted themselves past the preconceived notion of heaviness, reveling in spiteful abandon. Forget any traces of vocal melody, as late Johnny Morrow’s inhuman rasps rip souls to shreds. Their debut LP means to send the uninitiated running for the hills, so approach it after getting familiar with “Houdini” and “Odd Fellows Rest.” The hallmarks of the genre are still present in it, but hardcore takes more of the spotlight in order to make its sound even more abrasive. This EP is a feedback-laden, misanthropic, destructive punch in the face. Iron Monkey was also important for the globalization of sludge metal, hailing from Nottingham, England.

Neurosis

“Through Silver In Blood:” Starting out as more of a crust punk outfit, Oakland, Calif.’s Neurosis soon evolved into something much heavier. Sludge metal is certainly a massive component of this record, its affinity for meditative passages and experimental insanity solidify this band as the pioneers of post-metal. They showed the world sludginess did not have to be limited to worshiping Flags and Sabbaths. They are as interested in leaving room for introspection as they are in profoundly upsetting listeners. Tension-filled crescendos and hair raising atmosphere make feral intensity only the the tip of the iceberg, establishing Neurosis as true visionaries of where sludge metal could be taken after being firmly established within the underground music landscape.

Bell Witch

“Four Phantoms:” Released last year, this album stands as a beautifully executed case of sludge metal transcending its roots and exploring other mediums of expression. Injecting funeral doom — which combines extreme doom metal with funeral dirge music — and dark ambient into their music. The Seattle-based duo of drums and bass paint a gorgeously morose tapestry using tasteful minimalism and sprawling songwriting as their paintbrushes. “Four Phantoms” is not for those with a short attention span, but those who saturate themselves in the gargantuan songs will find emotional oblivion in snail-paced mourning. Bell Witch uses the abyssic heaviness of sludge metal as a springboard into new dimensions of leviathanic songwriting.