Earth and its extrusions reflected and carved

And yet even as they look organic, von Rydingsvard’s sculptures are also — self-evidently — made by human hands and tools. The artist emphasizes this by leaving her own marks and notations on the works’ surfaces. Her process varies with each piece. But it involves hard labor (stacking, gluing, and clamping cedar beams), challenging logistics, and lots of planning.

In 2008, von Rydingsvard won the Rappaport Prize, an award set up and sustained by Jerry and Phyllis Rappaport and dispensed by the deCordova. So even though this mid-career retrospective was organized by Helaine Posner for the SculptureCenter in Long Island City, N.Y., it is a return, of sorts, for von Rydingsvard.

The artist arranges and rearranges blocks of wood almost like collage, building up monumental forms from smaller sections, before setting to work with a circular saw to carve out their exterior shapes. She ends the process by covering parts of the surface with graphite, darkening the natural patina of the cedar.

Process is one thing. But do they work as sculptures? A lot of the time, yes. There are two tremendous pieces in the deCordova’s main gallery, and another one on the roof. All three instantly convince you of von Rydingsvard’s force as an artist, and of the originality of her achievement.

But a little too much in this show fails to get going. I suspect it’s because, even as von Rydingsvard has gouged out a powerful new language, she is not always so convincing when it comes to forms. Not unlike Chakaia Booker, who was the subject of a compelling survey show at the deCordova last summer, she can be mesmerizing one minute, and nerveless the next.

In both cases, the thrill of a new sculptural language (in Booker’s case it was cut up car tires) can occasionally run ahead of the artist’s capacity to unite that language with persuasive forms. The result is either willfully arbitrary shapes that don’t match the materials, or a tendency to fall back on clichéd motifs.