"Rock Post Rock," the third track on Polvo's new Shapes, is more of a stance than a song. With good guitar work that isn't afraid to rock, it brings to mind all that was good about Dinosaur Jr before J Mascis went all noodly on the guitar. Likewise, the title Shapes is as good a description as any for this album. It comes across like a 3-D relief map, with straight organic rock at its high points and structured geometric sound at the lows; the combination of the two varies throughout the album. At times, such as the aforementioned song and much of "D.D. (S.R.)," the organic component is thicker, and the guitar-rock sound obscures the underlying structure. On other songs, like the gargantuan but sparse "El Rocio" or the Sonic Youth-flavored "Enemy Insects," are representative of the map's low points: thin, hyper-structured, and somewhat cold. These sounds are not as extreme or opposed as you might think: As with any relief map or landscape, one feature does not simply drop out; it flows between the two, with one element smoothly giving way to the other. From start to finish, Shapes is the sort of journey that meanders through these elements in a way that deserves more attention than your average "post-rock" album. Polvo's genius shows through by achieving the difficult harmony between the structured and the chaotic.