Onkalo, the title of Oliver Barrett's sophomore Petrels outing, stands for ‘hiding place' and refers to a nuclear fuel repository currently under construction in Finland designed to house hazardous nuclear waste for a minimum of 100,000 years. That idea serves as a conceptual starting point for the release, though it's hardly the most pertinent thing about Barrett's Haeligewielle follow-up—more telling is the fact that no instrumentation details are included (a vocal credit for one track aside), a move that implies that the listener should fixate on the sound mass on its own terms rather than be sidetracked by who played what. Having said that, there's no denying that the album's imaginative track titles allude to possible narratives, some with positive overtones (“Hinkley Point Balloon Release”) and others more ominous (“Kindertransport”). Barrett's a sound designer who sequences blocks of variegated sounds—strings, organ, choral voices, electronics, etc.—into multi-layered compositions of ambitious scope and length, with two of the release's nine pieces ten minutes long and one twenty. He's largely his own man, too, though it is impossible to ignore the Steve Reich echo in the percussive patterns running through “Trim Tab pt. 2.”
A sense of wonder permeates Onkalo's opening pieces. “Hinkley Point Balloon Release” ushers in the album with the euphoric sweep of orchestral strings, after which “Giulio's Throat” uses crystalline elements to suggest some fantastic enchanted setting. Darkness gradually floods in, however, as embodied in the oscillating chords that swell until they all but obliterate the track's originating sounds. Interesting juxtapositions surface: during “On the Dark Great Sea,” the voices of Holly Stead and (presumably) Barrett act as a full-bodied vocal choir whose roar is heard alongside pounding drums—the classical and tribal conjoined. Contrasts occur between tracks, too, with the industrial heaviness of “Characterisation Level” followed by the strings-only “Kindertransport.” In this context, the presence of a funky techno rhythm (as occurs within “Trim Tab pt. 1”) is a surprise (if not a non sequitur) though not an unwelcome one.
One of the album's most powerful tracks is the twenty-minute “Characterisation Level,” which flirts with doom metal in the raw guitar-generated squalls that appear with crushing force. Barrett maintains a controlling hand throughout, however, as the molten material never turns into decimating feedback but instead undergoes a slow metamorphosis as its guitar elements are joined by electronic squiggles and symphonic strings pulsations. Fifteen minutes along, drums enter, advancing the evolution from industrial to a style more akin to rampaging krautrock.
An elegiac feel infuses some pieces, including “Time Buries the Door,” where hurdy gurdy-like melodies flutter plaintively amidst churning strings and percussion, and “Kindertransport,” a beautiful and keening setting whose title, intentional or not, evokes the image of a train packed with children bound for a WWII concentration camp. Too often the word journey is used to describe an album, but it's warranted in the case of Onkalo. The listener truly does feel as if he/she starts in one place and ends up somewhere entirely different, and the stopping points along the way are consistently unpredictable.