Form: Intro → A theme (trumpet call, horn answer, strings 8th-ostinato in 6/8) → fill → B second subject in G (oboe lead, violin answers, the ostinato drops to a pizz-and-harp barcarolle) → fill → A′ (the theme in borrowed F major: horns carry it, trumpet takes the soaring phrase and a descant, low brass underneath) → RAPIDS (D-minor set-piece: tremolo waves, timpani rolls, 3+3 vs 2+2+2 hemiola brass) → coda → loops to A. Click the timeline to jump. Layers: the headway slider adds stems at the barline — lead, then woodwind runs and violin doubling, then brass accents and snare pressure; impacts duck the score. All voices are the platform's sampled instruments; river and forest beds run underneath. Press Space to start.