Original 1st printing 13 x 19&7/8" double-sided concert poster for a pair of 1970 concerts held at Mammoth Gardens in Denver, CO featuring the Grateful Dead appearing with John Hammond on 4/24-25 and Jethro Tull appearing with Zephyr (featuring Tommy Bolin) and Clouds (with Billy Cobham) on 4/17-18.
Art by B. Warren, medium-thick textured index stock poster is in used (B-) condition; a heavy amount of edge wear, several decent-sized edge tears, creasing, moisture staining, a bit of white paint residue in the lower right margin, surface wear (chipping/scuffing), toning, a couple of small pulls, multiple pin holes in the corners, etc.... it's pretty obvious that this example was pulled down from public display in 1970.
Conditional issues aside, this is still a VERY, VERY scarce low-run 1st printing regional Dead concert poster from one of their most fertile periods. A tape from the 4/24 show exists (a little rough in sound quality, but all there), check it out HERE:
https://archive.org/details/gd70-04-24.aud.hanno.19531.sbeok.shnf