The arrival of archival releases from the Grateful Dead and Jerry Garcia solo projects has its own distinct flow, much like the Dead themselves. Not every set will seem a gem to every listener. More, though, each provides an excuse for momentary time travel, a night out with Garcia, plus plenty of historical sites to hear and ponder along the way.

Dave’s Picks, Volume 19 lands Dead freaks in Hawaii for a weekend in January 1970, the last shows with keyboardist Tom Constanten, and a slice of the Grateful Dead with everything in its right place. The twonight/ three-disc stay tilts more toward country-boogie than psychedelia, but there’s still a primo 18-minute “Dark Star” with a ghostly glockenspiel. There’s, likewise, the question of who’s singing with Pigpen early in the 46-minute “Turn on Your Love Light” (twice the length of “Dark Star”). Is it opening act Michael J. Brody, a longhaired oleomargerine heir intent on giving away his fortune? Probably not, but he’s a good wormhole.

Retrieved from a stash of Keith and Donna Jean Godchaux’s personal tapes and previously unheard as a Betty Cantor-recorded soundboard, GarciaLive, Volume 7 drops the listener on a Tuesday night in November 1976 at Sophie’s, a few months before the venue transformed into the Keystone Palo Alto, a live music dive that soundtracked the birth of Silicon Valley. Though the date might actually be the following week, per an audience taper’s notes, GarciaLive presents a random night from the Garcia Band’s golden age. With Elvis Presley drum-god Ron Tutt hanging back, Jerry & Co. get lost in the slow-motion reggae-gospel of “Don’t Let Go” and “Who Was John?” and elsewhere, headed for the wide, warm space between sleep and boogie. A postcard from Garcia’s extra-Dead oasis, it’s a space quiet enough for whispered musical conversations (“Friend of the Devil”) and Donna Jean vocal leads (“Strange Man”).