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Visualizing Grand Canyon Stratigraphy – A fresh holistic approach

The wonders of the Grand Canyon cannot be adequately represented in symbols of speech, nor by speech itself. The resources of the graphic art are taxed beyond their powers in attempting to portray its features. Language and illustration combined must fail.” John Wesley Powell

Note: Page down for blog summary en español.

Over the past several years several excellent stratigraphic sections have captured the iconic stratigraphy of Grand Canyon (e.g. Karlstrom and others (2008); Gootee (2019), Billingsley and others (2019). Bob Leighty’s new, holistic stratigraphic column, Grand Canyon Stratigraphy, is a valuable and creative contribution to these efforts. Scholars and students of Grand Canyon geology will find that this fresh stratigraphic section nicely complements the many excellent treatises (e.g., Billingsley, 2000; Beus & Morales, 2002) and popular geology maps and texts on the Canyon.

AZGS’ Brian Gootee said of Bob’s stratigraphic column, “An excellent compilation and visual presentation of Grand Canyon stratigraphy for enthusiasts, general public, and professionals.”

Leighty - Grand Canyon Stratigraphy
The upper portion of Grand Canyon strata.

The ‘Grand Canyon Stratigraphy’ incorporates all of the usual strat column features: geologic time, lithologies and rock units. The Lithologies section boasts nearly 40 radiogenic age dates tracking the temporal evolution of strata exposed in Grand Canyon. It includes a rich suite of symbols representing key sedimentary features and structures: fossils, mud cracks, cross bedding, convoluted bedding, to name a few. Structural features, isoclinal folds and boudinage, are also symbolized. Rock unit descriptions are terse but adequate; sedimentary rock descriptions are accompanied by a brief note on depositional environment.

To assist the untrained geology enthusiast, the ‘Important Terms’ box translates geologic lexicon into plain-spoken English, e.g., fluvial = stream-related and protolith = original rock type; isoclinal = parallel fold limbs. The ‘Canyon Etymology’ box sheds light on the meaning of the many esoteric canyon names (e.g., Vishnu (Hindu) – the god of preservation and protection; Toroweap (Paiute) – arroyo or dry wash).
The ‘Tectonic History’ box demarcates the five major tectonic events that shaped the rocks exposed in Grand Canyon. One dozen ‘Field Geology’ annotated photographs wonderfully capture both the geology and spectacular beauty of Grand Canyon from the youngest to the oldest rocks.

An abridged ‘Reference’ list includes citations for both popular geologic texts (e.g., Abbott and Cook, 2007, “Geology Underfoot in Northern Arizona”) and essential technical papers (e.g., Karlstrom and others (2018), “Cambrian Sauk transgression in the Grand Canyon redefined by detrital zircons”).
At full size ‘Grand Canyon Stratigraphy’ measures 24” wide by 54” tall, thus incompatible with the small screens of a smart phone or tablet. This product is best printed or viewed on computer monitor, and it’s ideal for educational use in the classroom or field. Printing the poster via Kinko’s online service would run ~$60.00.

Spanish summary:  Visualización de la estratigrafía del Gran Cañón: un nuevo enfoque holístico

En los últimos años, varias secciones estratigráficas han capturado la estratigrafía icónica del Gran Cañón (por ejemplo, Karlstrom et al., 2008; Gootee 2019; Billingsley et al., 2019). La nueva columna estratigráfica holística de Bob Leighty, Grand Canyon Stratigraphy, es una contribución valiosa y creativa a estos esfuerzos. Académicos, profesionales, estudiantes y publico en general con interés en la geología del Gran Cañón encontrarán que esta nueva sección estratigráfica complementa el excelente trabajo de autores anteriores (por ejemplo, mapas y textos de geología popular sobre el Gran Cañón).

‘Grand Canyon Stratigraphy’ incorpora todas las características habituales de la columnas de estratos: tiempo geológico, litologías y unidades de roca. La sección de Litologías cuenta con casi 40 edades radiogénicas que siguen la evolución temporal de los estratos expuestos en el Gran Cañón. Incluye símbolos que representan características sedimentarias y estructuras claves: fósiles, grietas de desecación, estratificación/laminación cruzada, estratificación convoluta, por nombrar algunos. También se simbolizan las características estructurales, los pliegues isoclinales y boudinage. Las descripciones de las unidades de roca son concisas pero adecuadas; las descripciones de las rocas sedimentarias van acompañadas de una breve nota sobre el entorno deposicional.  (Translation by Victor Higareda Garcia.)

Para mas información visite:


  • Abbott L. and Cook, T., 2007, Geology Underfoot in Northern Arizona. Mountain Press, Missoula, MT, 327 p.
  • Beus, S.S. and Morales, M. (eds), 2002, Grand Canyon Geology. Oxford University Press, 2nd edition, 448 p.
  • Billingsley, G.H., 2000, Geologic map of the Grand Canyon 30' x 60' quadrangle, Coconino and Mohave Counties, northwestern Arizona. US Geological Survey IMap 2688 (DO  - 10.3133/i2688) 
  • Billingsley, G.H., Goodwin, G., Nagorsen, S.E., Erdman, M.E., and Sherba, J.T., 2019, Geologic field photograph map of the Grand Canyon region, 1967–2010: U.S. Geological Survey General Information Product 189, 11 p.
  • Gootee, B.F., 2019, Geologic Timeframe of the Grand Canyon. Arizona Geological Survey Open-File Report OFR-18-02, with Supplemental resource document for Geologic Timeline of the Grand Canyon 2 p.
  • Karlstrom, K., Semken, S., Crossey, L., Perry, D., Gyllenhaal, E.D., Dodick, J., Williams, M., Hellmich-Bryan, J., Crow, R., Watts, N.B. and Ault, C., 2008. Informal geoscience education on a grand scale: The trail of time exhibition at Grand Canyon. Journal of Geoscience Education, 56(4), pp.354-361.
  • Leighty, R.S., 2021, Grand Canyon Stratigraphy. Arizona Geological Survey Contributed Report CR-21-D, poster 24x54 inches.