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Penn State Abington College

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J. Alcock

Professor of Geociences

College of Earth and Mineral Sciences

Division of Science and Engineering

Abington College

General  Expertise Research Experience GEOBOTS Courses Maps of the PA-DE Piedmont Virtual Geology of Wissahickon Creek, Fairmount Park: Valley Green Bell's Mill Road

Teaching and learning are active processes. Because the majority of my students are not science majors, I have the opportunity to create courses that stress methods of thinking and investigation through a combination of lecture, field trips, and laboratory activities. I want to challenge students to change their world view as they master new skills that increase their power as thinkers and questioners.

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General Information

Penn State Abington College
1600 Woodland Road
Abington, PA. 19001-3990

Telephone: (215) 881-7356
Fax: (215) 881-7623
Email: jea4@psu.edu

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Area of Expertise

Metamorphic petrology is the study of rocks that have experienced chemical changes as a result of changing temperature and/or pressure. When combined with field data, metamorphic petrology provides a window open to the geologic past. Studies of this kind are particularly relevant to understanding events that formed and destroyed mountains. For example, the rocks of the Abington Campus are metamorphic rocks that were buried 20 to 30 km. beneath the Earth's surface. They were metamorphosed when a Japan-scale block of continental crust moved across an ocean and collided with what is now PA nearly 450 million years ago. The collision formed high mountain ranges similar to the Alps and Andes of today. The mountains have disappeared, eroded by ice and rain, but the rocks that were buried beneath them are now exposed at the surface and give evidence of their existence.

I have also become interested in the use of systems and graphical analysis to predict the behavior of Earth Systems.  A recent paper in the on-line journal Earth Interactions (http://www.earthinteractions.org/) looks at feedback and its potential to cause catastrophic environmental change in the Amazon Basin in response to deforestation.

Research Interests

Orthopyroxene separates plagioclase (gray) from clinopyroxene (yellow). Evidence of changing conditions during metamorphism in the Adirondacks.
 

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Professional Experience

Member of the Penn State University Department of Environmental Sciences since 1989.
Instructor at the University of Pennsylvania-YBRA summer field course in geology since 1992.

Education:

Ph D in Geology, University of Pennsylvania, 1989.
M Ed in Science Education, Temple University, 1976.
B A in Spanish, Haverford College, 1968.

Selected Publications and Papers:

Alcock, J., 1994, The discordant Doe Run thrust: Implications for stratigraphy and structure in the Glenarm Super Group, southeastern Pennsylvania Piedmont, Geological Society of America, Bulletin, v. 106, p. 932-941.

Alcock, J., and Wagner, M. E., 1995, Metamorphic discontinuities in the Pennsylvania-Delaware Piedmont: evidence for early Paleozoic assembly, Canadian Journal of Earth Science, v. 32, p. 686-698.

Alcock, J., 1996, Effect of grossular on garnet-biotite Fe-Mg exchange, evidence from natural garnet with mixed growth and diffusion zoning, Contributions to Mineralogy and Petrology, v. 124, p. 209-215.

Alcock, J. and Muller, P. D. 1999a, Very high temperature, moderate pressure metamorphism in the New Russia gneiss complex, northeastern Adirondack Highlands, metamorphic aureole of the Marcy anorthosite.  Canadian Journal of Earth Science, v. 36, p. 1-13.

Alcock, J., Myer, K., and Muller, P. D. 1999b,  Three-dimensional model of heat flow in the aureole of the Marcy anorthosite, Adirondack Highlands, New York:  Implications for depth of emplacement.  Geological Materials Research, v.1, n. 4, p. 1-27 .

Alcock, J. and Muller, Peter, 2000, Anatexis at 700 to 1000 MPa in the aureole of the Marcy anorthosite, Adirondack Highlands, New York.  Contributions to Mineralogy and Petrology, v.139, p. 643-654.

Alcock J., 2003, Positive feedback and system resilience from graphical and finite-difference models: The Amazon ecosystem, an example. Earth Interactions, v. 7, n. 5. (Alternative link to PDF file)


Alcock, J., Isachsen, C., Livi, K., and Muller, P., 2004, Unraveling complex growth histories of zircon in anatectites, constraints on model PTt paths for the NE Adirondack Highlands, NY. in Tollo, R.P., Corriveau, L., McLelland, J. , and. Bartholomew, M.J., eds., Proterozoic Tectonic Evolution of the Grenville Orogen in North America, Boulder, CO, Geological Society of America Memoir 197, p. 267-284.


Alcock, J; Arenas, R; Martinez Catalan, J R, 2005, Shear stress in subducting continental margin from high-pressure, moderate-temperature metamorphism in the Ordenes Complex, Galicia, NW Spain. Tectonophysics, V. 397, p. 181-194.


Alcock J, 2005, An algorithm for computation of the steady-state thermal structure of mature subduction zones, Computers & Geosciences, V. 31, P. 1071-1074.

Alcock, J. and Muller, P., 1996, Very high-temperature, moderate to high-pressure metamorphism, eastern Adirondack Highlands: Evidence for deep emplacement of massif anorthosite. Geological Society of America, Abstracts with Programs, Northeastern Section, Vol. 28, No. 1, p. (Buffalo, NY.)

Muller, P. and Alcock, J., 1996, Contrasting absolute and relative ages, Adirondack Highlands, northeastern U. S., does the granulite uncertainty principle extend to U-Pb metamorphic ages? Presented at the 12th International Conference on Basement Tectonics. (Goosebay, Labrador).

Alcock, J. and Muller, P., 1998, The Marcy anorthosite emplaced at a depth of 30 km, geobarometric evidence from its aureole, NE Adirondack Highlands, NY.  Geological Society of America, Abstracts with Programs, Vol. 30, No. 7, p. 229 (Toronto, Ont).

Alcock, J., Isachsen, C., Livi, K., and Muller, P., 2000, High-resolution thermal history for migmatites from integrated electron microbeam, cathode luminescence, and isotopic dilution analyses.  15th International Conference on Basement Tectonics, Programs and Abstracts, p. 35 (A Coruña, Spain).


Alcock, J., Isachsen, C., and Muller, P., 2001, Conditions and timing of emplacement of the Marcy anorthosite, NE Adirondack Highlands, inferred from anatectites in its aureole: Part 1, Field relationships and P-T estimates. Geological Society of America, Abstracts with Programs, Vol. 33, No. 6, p. 292 (Boston, MA).

Alcock, J., 2001, Stable and unstable states in a system controlled by positive feedback, implications for the tropical rainforest ecosystem. GSA-GSL Earth System Processes Meeting, Edinburgh, UK.


Alcock, J., 2002, Multiple steady states created by positive feedback and their effects on system response to perturbation. Geological Society of America, Abstracts with Programs, Vol. 34, No. 6, p. 241 (Denver, CO).

Alcock, J. 2003,  Milankovitch cycles, positive feedback and system switching between stable states, a model for glacial – interglacial repetitions. Geological Society of America, Abstracts with Programs, Vol. 34, No. 7, p. 481 (Seattle, WA).


Alcock, J., Arenas, R., and Martínez Catalán, J.R., 2004, Shear stress and negative feedback in subducting continental margin, impact on high-pressure, moderate-temperature metamorphism, in the Ordenes Complex, Galicia, NW Spain. Northeastern Section, Geological Society of America, Tysons Corner, VA.


Alcock, J; Muller, Peter D; Haugh, Joshua, 2005, Contact metamorphism in pelitic gneiss adjacent to Wolf Creek ultramafic body, Ruby Range, SW Montana, evidence for hot emplacement Geological Society of America, Abstracts with Programs, vol.37, no.6, p. 42, Apr 2005.

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GEOBOTS

GEOBOTS -- Engineering and geoscience students working together to research robotic data collection.


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Course Information

Geoscience 020


Geography 010

Earth 002

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