Missoula Floods

Missoula release attribution

Require a stated evidential basis for connecting an inferred flood to the source lake rather than merely to regional flooding.

1. What evidence connects this candidate episode to a release from glacial Lake Missoula? provenance
2. Could the same evidence represent a Bonneville flood, an independent Lake Columbia release or an unresolved combination? boundary

Episode individuation

Treat episode labels as interpretations requiring correlation, rather than assuming each exposure records a separate flood.

1. What separates this proposed episode from adjacent pulses, deposits or other reconstructed floods? definition
2. Which observations show that differently named local records represent the same release? provenance

Age and bracketing

Record whether a date measures flood deposition or only constrains it from above or below.

1. What was dated, by which method, and how does that material constrain the flood's age? measurement
2. Which timescale, calibration and uncertainty accompany the proposed beginning and end of the series? boundary
3. Which publication or synthesis establishes the adopted dating convention? provenance

Preserved versus total count

Separate local counts from series-wide estimates; annual-layer interpretations can inform recurrence but require explicit assumptions. [USGS study](https://www.usgs.gov/publications/case-periodic-colossal-jokulhlaups-pleistocene-glacial-lake-missoula)

1. Is this count a preserved minimum, a correlated regional count or an extrapolated total? measurement
2. How were annual layers identified, and could erosion or nondeposition alter the inferred interepisode interval? provenance
3. Which episode correlations must hold before these local counts can be combined? boundary

Available release water

Distinguish estimated lake capacity from water actually released during a particular episode.

1. Which shoreline, topographic or ice-margin evidence constrains the lake level before this release? provenance
2. What released volume is compatible with those constraints, and how much drainage is assumed? measurement

Release mechanism hypotheses

Retain competing explanations of dam failure and reimpoundment with their authors and testable implications.

1. Which investigator proposes each release mechanism, and what evidence distinguishes the alternatives? provenance
2. What lake, ice and drainage conditions must hold for the proposed mechanism? definition
3. Is renewed impoundment supported for this interval, or inferred only from the existence of a later flood? boundary

Episode route configuration

Evaluate evidence for passage through the scabland and Columbia corridors, including proposed ponding and backflooding near Wallula Gap.

1. Which passages were available under the ice-margin configuration assigned to this episode? boundary
2. What observations distinguish downstream flow from ponding or backflooding at the mapped location? provenance
3. Does the map depict one reconstructed flood or the union of routes used at different times? definition

Comparable magnitude estimates

Attach discharge and inundation estimates to a reach and episode; published work combines field evidence, dating and hydraulic modelling. [USGS hydraulic study](https://www.usgs.gov/publications/number-and-size-last-glacial-missoula-floods-columbia-river-valley-between-pasco-basin)

1. At what reach and for which episode are peak discharge, depth or duration estimated? measurement
2. How sensitive is the result to reconstructed topography, roughness, ice blockage and the assumed release hydrograph? measurement
3. Are the assumptions sufficiently aligned to compare or combine these two estimates? action

Trace-to-event attribution

Record observations of scoured channels, bars, transported boulders and slackwater beds separately from their proposed flood origin.

1. Which measured properties support Missoula flood erosion or deposition at this site? provenance
2. Could later floods, reworking or other processes account for part of the feature? boundary
3. What independent marker supports assigning this feature to a particular episode? measurement

Competing flood interpretations

Separate disagreements about episode number and bed interpretation from disagreements about source, route or magnitude. A historical study explicitly evaluated successive beds as evidence for separate floods. [USGS stratigraphic study](https://www.usgs.gov/publications/tens-successive-colossal-missoula-floods-north-and-east-margins-channeled-scabland)

1. Which specific claim is disputed, by whom, and on what observational grounds? provenance
2. What additional observation would distinguish the competing interpretations? action
3. Which conclusions can an agent present as supported, and which require an explicit uncertainty statement? action

Check these first

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these check these first hold for the sense of Missoula Floods this model covers, and on what evidence? provenance

Real-world use

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these real-world use hold for the sense of Missoula Floods this model covers, and on what evidence? provenance

Failure modes and hazards

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these failure modes and hazards hold for the sense of Missoula Floods this model covers, and on what evidence? provenance

Regional variation

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these regional variation hold for the sense of Missoula Floods this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of Missoula Floods this model covers, and on what evidence? provenance