[DSRP Evidence](https://dsrpevidence.org/)

# Stratigraphic architecture and hierarchy of fluvial overbank splay deposits

## Details

**Authors** Burns, C. E. and Mountney, Nigel P. and Hodgson, David Mark and Colombera, Luca

**Year** 2019

**Publisher** Journal of the Geological Society, vol. 176, no. 4, pp. 629–649

**Kind of work** article

**Discipline** Geology

**Applied** false

[Read it at the publisher](https://doi.org/10.1144/jgs2019-001) 
10.1144/jgs2019-001

## In authors' words

### What they set out to do (purpose)

To propose a hierarchical classification of splay deposits, the sand-prone units within fine-grained floodplain successions, and to identify the controls on their stratal architecture.

### Who or what was studied (sample)

Outcrop data from eleven exhumed sites in the Jurassic Morrison Formation and the Cretaceous Mesaverde Group (western USA), including 104 graphic logs (1,241 m cumulative) and 67 splay elements characterized in detail, with 11 complexes identified; satellite-image analysis of splays on nine modern rivers.

### How they did it (methods)

Field measurement of graphic logs and architectural characterization of splay bodies, with recognition criteria based on bounding surfaces, thinning and fining trends, and palaeocurrent variability; comparison with modern analogues; mapping of splay deposits from three previously studied successions onto the proposed scheme.

### What they found (results)

Splay deposits are organized into four tiers: lithofacies, beds, elements, and complexes. Single-bed splays were the most common type (about 60–71% across formations). Neslen Formation crevasse splays averaged about 1,072 m in width and 1.4 m in thickness; Morrison crevasse splays were smaller (about 181 m wide, 0.9 m thick). Compensational stacking was recognized in the ancient successions and progradational stacking only in the modern examples. Stratal architecture depends on the rate of local accommodation generation, floodplain topographic confinement, and the migration direction of the parent channel. Splays from other studied successions map onto the scheme despite differing terminology.

## Commentary

### In short

The study classifies floodplain splay deposits into four nested tiers, from individual lithofacies up to complexes, using outcrop data from two formations and modern river imagery. It also identifies what controls how these deposits stack.

### Response

The classification is a case of nested part-whole structure: lithofacies compose beds, beds compose elements, and elements compose complexes, with bounding surfaces and thinning and fining trends serving as the distinctions that mark each tier's edge. The reported controls on stacking (accommodation generation, confinement, channel migration) are relationships between the deposit and its depositional setting. The fit with distinctions is partly a matter of classification practice generally, and the paper does not treat the choice of tiers as perspective-dependent, so perspectives are not claimed.

**Patterns it shows** D, S, R

Shows the structure is there

**Added** 2026-10-28

**How to cite this** Burns, C. E. and Mountney, Nigel P. and Hodgson, David Mark and Colombera, Luca (2019). Stratigraphic architecture and hierarchy of fluvial overbank splay deposits. Journal of the Geological Society, vol. 176, no. 4, pp. 629–649.