Year: 2026

Instrumentation: Chamber Orchestra (1110/0110/Perc/Organ/Strings 1111)

Flute (db. Piccolo/Baking Tray or squarish metal object with Mallet)
Oboe
Clarinet in Bb (db. Bass Clarinet)

Trumpet (straight mute)
Trombone (harmon mute and straight mute)

Percussion                                                                   

Bass Drum / Bongos (with ruler or flexible mallet) / 2 Guiros / Glockenspiel / Hi-hat / Suspended Cymbal (with bow and water container to dip into) / Snare Drum (positioned upside down on stand with wires facing up, snare engaged, but tension loose so wires rattle) / Tam-tam (with coin) / Timpani / Triangle / Thai Gongs / 5 Woodblocks

Hammond Organ (or Church Organ/Synthesizer with Organ Settings)

Violin (db. Baking Tray or squarish metal object with Mallet)
Viola (share single Thai Gong (C4) with Percussion)
Violoncello
Double Bass

Duration: 16:30″

Performance History: Commissioned by Huddersfield Contemporary Music Festival. First performed by Collegium Novum Zürich and Dominik Blum (organ) of Steamboat Switzerland, conducted by Titus Engel in Zürich and Huddersfield in November 2026. https://cnz.ch/ali-wertmueller-mcdonnell-steamboat-switzerland
https://hcmf.co.uk/programme/collegium-novum-zurich-steamboat-switzerland/

About:
Retrogressive Thaw Slump is a type of dynamic and recurring landslide which occurs when vast layers of permafrost thaw rapidly, often precipitated by terrain disturbances such as construction, forest-felling, and rising temperatures. As each layer of ice melts away a new surface is exposed, leading to further collapse as the accumulated sediment erodes further into the landscape, with some of the largest slumps creating scars hundreds of feet deep. My composition takes the idea of a descent through melting layers as its starting point, with the musical materials colliding, cracking, warping and scraping until other surfaces becomes exposed underneath. The inclusion of the Hammond Organ in the ensemble (and my thanks to Dominik Blum for answering many questions about the instrument) inspired me to draw on my roots as a rock musician, and some of the timbral and rhythmic choices are inspired by progressive and experimental rock musicians like Frank Zappa, Gentle Giant, and King Crimson.

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