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Gary D. Johnson

Sedimentology and Paleontology

 

 

Contact Information:

 
Dartmouth College
Department of Earth Sciences
6105 Fairchild Hall
Hanover, NH 03755
 
Email: gary.johnson@dartmouth.edu
Office: 408 Fairchild
Office Phone: 603-646-2371
Office Fax: 603-646-3922

 

Summary of Research Intrests:

My research activity focuses on the terrestrial record of several regions of significant environmental and tectonic change. This includes both mid-Mesozoic as well as Neogene-aged sedimentary assemblages.  This research has been primarily been on areas of the East African rift system, mainly in northern Kenya, as well as in the evolving Himalayan foreland basin of north India and Pakistan.  New initiatives related to a variety of sedimentary geologic problems in New England and in the northern Rockies of Wyoming, as well as research into the paleontologic record of ratite bird (e.g. Struthio sp. – ostrich, and Aepyornis sp. – “elephant bird”?) evolution and distribution in Europe and Asia is the focus of current research.

The sedimentary record of cratonic basins often provides a window into the pre-orogenic and orogenic history of adjacent mountain belts. The facies character of this sedimentary fill can usually be linked to various autocyclic and allocyclic controls, but difficulties in sorting out the chronometric detail oftentimes makes for uncertain temporal relationships. Work presently being conducted on certain Mesozoic sediments of the Cordilleran foreland basin of Wyoming and Montana, and in Late Neogene sedimentary record of the Himalayan foreland basin in India and Pakistan, is focused on understanding the detail of foreland basin evolution and the sedimentological character of syn-orogenic deposition in areas where high quality chronometric control can be erected. In this research, most of the sedimentary successions are terrestrial in character, and while having a reasonably well defined vertebrate biochronology, oftentimes these successions do not permit precise temporal relationships to be defined amongst various localities and related successions. Much of this work then, is coordinated with series of collateral studies on the chronostratigraphy of these same deposits, through separate studies of their magnetic polarity stratigraphy, and in some cases their tephrochronology.

One of these current initiatives, the peritidal record of a number of marginal marine sedimentary sequences and their tidal record, is currently underway, and involves an assessment of the character of the tidal signature preserved in Champlain Sea (early Holocene) sediments of Quebec, Ontario, and northernmost New England. 

Additionally, my work has increasingly focused on public service geological research and consulting, where I am closely involved with the U.S. Bureau of Land Mangement (Department of Interior) in developing educational and research protocols associated with paleontologically important public land resources in Wyoming and elsewhere.  This work has also extended to assisting several natural history museums in Wyoming in outreach development.

Current contractual arrangements with the Wyoming State Geological Survey exist to develop and produce quadrangle-scale geological maps of portions of that state.  To date, one map has been completed, and several additional maps, at varying scales (1:24,000; 1:100,000) are in review or in preparation. 

 

Research: Stratigraphic Studies (pdf)

Upcoming Intro Classes: EARS 8 - The Geology of New England and Surrounding Areas (pdf)

Selected Recent Publications:

Adams, K. and G. D. Johnson, 2006, Tidal? rhythmites of the Late Wisconsinan Champlain Sea,  Geological Society of America Abstracts with Programs, Vol. 38, No. 2, p. 29

Adams, K. E., Johnson, G. D., and E. S. Posmentier, 2007, Tidal record preserved in marginal sediments of the Late Wisconsinan Champlain Sea, Geological Society of America Abstracts with Programs, Vol. 39, No. 1, p. 91

Johnson, G.D., 2008.  Geochronology:  The interpretation and dating of the geological record – Introduction;  Study of the rock record (in part), Encyclopædia Britannica, 2008, On-line edition,  Macropædia.

Kvale, E. P., Mickelson, D.M., Johnson, G. D., and S. Hasiotis, 2005, The history of dinosaur footprint discoveries in Wyoming, with emphasis on the Bighorn Basin, In, S.G. Pemberton, ed., A special volume to commemorate the contributions of W.A.S. Sarjeant, Ichnos, v. 11, pp. 3-9.

Kvale, E.P., G.D. Johnson, D.L. Mickelson, K. Keller, L.C.Furer, and A. W. Archer, 2001. Middle Jurassic (Bajocian and Bathonian) dinosaur megatracksites, Bighorn Basin, Wyoming, U.S.A., Palaeos. v. 16, no. 3, pp. 233-254.

Kvale, E.P., S. T. Hasiotis, D.L. Mickelson and G.D. Johnson, 2001, Middle and Late Jurassic dinosaur fossil-bearing horizons: Implications for dinosaur paleoecology, northeastern Bighorn Basin, Wyoming, in C.L. Hill, ed., Mesozoic and Cenozoic paleontology in the Western Plains and Rocky Mountains, Society of Vertebrate Paleontology - 61st Annual Meeting, Bozeman, MT, October, 2001, Guidebook for the field trips. Museum of the Rockies Occasional Paper No. 3, pp. 15-46.

Pivnik, D.A. and G.D. Johnson, 1995. Depositional response to Plio-Pleistocene foreland partitioning in northwest Pakistan. Geol. Soc. America Bulletin, v. 107, no. 8, pp. 895-922.

Reeder, D., G.D. Johnson and R.W. Birnie, On-demand, Geologic map of the Manderson NE Quadrangle, Big Horn Co., Wyoming, Scale:  1:24,000 (7.5 minute geological quadrangle series), Wyoming State Geological Survey, Laramie, WY.

Renshaw, C.E., Johnson, G.D. and K.F. Kvale, 2000, A laboratory exercise on determining dinosaur speeds using dimensional analysis. Journal of Geoscience Education, v. 48, pp. 342-346.

Swierc, J. and G.D. Johnson, 1996. A local chronostratigraphy for the Morrison Formation, northeastern Bighorn Basin, Wyoming, in C.E. Bowen, S.C. Kirkwood and T.S. Miller, eds., Resources of the Bighorn Basin. Wyoming Geological Association Guidebook (47th). pp. 315-327.

 

 

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