Lately Ryan Adams has been revisiting the country rock of his early career: first with Cold Roses, the two-disc set Adams and his band the Cardinals put out just a few months ago; and now on Jacksonville City Nights, an unadulterated return to form. Nights finds him digging deeper than ever into the genre to suckle on its dirt-clotted roots. Adams stakes out a fairly small plot of land, which gives these fourteen tracks a purity of spirit: He explores with unwavering dedication the shuffle, sway and gallop of traditional country music, as channeled through the filter of Seventies country rock. Taking cues from Southern bards such as Gram Parsons and Townes Van Zandt, Jacksonville City Nights is also classic Adams — earthy, rich with pathos and almost disconcertingly dedicated to the idea that life’s only two constants are losing a lover you probably didn’t deserve in the first place and losing yourself in the bottom of a fifth of Jack Daniel’s. The standout tracks are the ones where a wearily bowed fiddle or heavy-hearted piano vamp matches Adams’ wounded honky-tonk moan. On the haunting ballad “Dear John” — a duet with Norah Jones, who ought to make a country album of her own — the devil is in the details of a marriage gone wrong: overdue bills, a miscarriage, the cats who “went missing from the window you never fixed and the door you never latched.” The prolific Adams has got another album due before year’s end. If Jacksonville City Nights is any indication of where he’s headed, we could be on the cusp of his best one yet.