Photomicrograph of a zoned plagioclase crystal from an andesite collected from the Chalupas caldera in Ecuador.

The peak of Cotopaxi volcano emerges from the clouds on a stormy day in the Ecuadoran Andes

The sun sets over Eagle Lake, northern California

Wild horses walk through early morning frost in the Chalupas caldera, Ecuador. Volcan Quilindana sits in the background.

A chain of cinder cones in the Mexican Volcanic Belt

Courses::Papers and Publications::Research Projects::Professional Associations

Courses that I teach::

• GEOL 05: Geology of Mexico
• GEOL 10: Physical Geology
• GEOL 10L: Physical Geology Lab
• GEOL 100: Mineralogy
• GEOL 125: Metallic Ore Deposits

Publications ::

Hammersley, L. & DePaolo, D.J., 2006, Isotopic and geophysical constraints on the structure and evolution of the Clear Lake volcanic system. Journal of Volcanology and Geothermal Research 153, 331-356

Blatter, D. & Hammersley, L., Impact of the Orozco Fracture Zone on the central Mexican Volcanic Belt. Journal of Volcanology and Geothermal Research (in press)

Hammersley, L., DePaolo, D.J., Beate, B. & Deino, A., Quantitative model for andesite and rhyolite generation in a continental margin volcanic arc: The Chalupas caldera, Ecuador. Revised manuscript in revision.

Abstracts ::

Hammersley, L. & Biskowski, M., 2008. Source characterization of stone grinding tools from the Teotihuacan Valley, Mexico. Abstracts with Programs, Geological Society of America. Vol. 40.

Hammersley, L., Kusnick, J., Cornwell, K. & Hausback, B., 2008. Attracting Hispanic students to the Geosciences through the development of introductory level Geology of Mexico and Mexico Field Trip courses and collaboration with minority-serving groups on campus. Abstracts with Programs, Geological Society of America. Vol. 40.

Stout, C.M., Hammersley, L. & Clynne, M.A., 2007. Field measurements of mafic enclave population density at Chaos Crags, Lassen Volcanic National Park, CA and implications for magma mixing. GSA Abstracts with Programs, Cordilleran Section.

Blatter, D.L. & Hammersley, L., 2006. A gap in the central Mexican volcanic belt: A result of shallow subduction of the Orozca fracture zone? Geological Society of America, Backbone of the Americas - Patagonia to Alaska

Hammersley, L. & DePaolo, D.J., 2004. Isotopic and geophysical constraints on the structure and evolution of the Clear Lake volcanic field. Geological Society of America Abstracts with Programs, Vol. 36, No. 5, p247

Hammersley, L. & DePaolo, D.J., 2002. Oxygen Isotope Evidence for the Role of Crustal Contamination in the Evolution of the Chalupas Caldera System, Northern Andes, Ecuador. AGU Annual Fall Meeting.

Hammersley, L. & DePaolo, D.J., 2001. Two-stage AFC-FC model for the evolution of large-volume rhyolitic ignimbrites (LRI’s). AGU Annual Fall Meeting.

Hammersley, Lisa., Feineman, Maureen D., Bryce, Julia G., and Carmichael, Ian S.E., 2001. A wet volcanic front in Mexico: The source of hydrous intermediate lavas. GSA Annual Meeting.

Feineman M.D., Hammersley L., Bryce J.G. and Carmichael I.S.E., 2001. Compositional consequences of lawsonite breakdown in regions of warm subduction. GSA Annual Meeting.

Hammersley, L., DePaolo, D.J. & Beate, B., 2001. Development of Large-Volume rhyolitic ignimbrites (LRI’s): Chalupas caldera, Ecuador. III South American Symposium on Isotope Geochemistry.

Hammersley, L., DePaolo, D.J. & Beate, B., 2000. Chalupas Caldera, Ecuador: A study of the development of a large volume rhyolite system in the northern Andes. IAVCEI General Assembly.

Hammersley, L. & DePaolo, D.J., 1999. Magma recharge and crustal assimilation in the evolution of the Clear Lake volcanic field, CA: An isotopic study. GSA Annual Meeting.

Research Projects/Interests ::

I am interested in the evolution of magma as it travels from the source to the surface. In particular I am interested in the evolution of very large volume, rhyolitic eruptions, some of the most devastating geologic events in Earth's history.

I use major and trace element chemistry of lavas to try to understand the source of the magma and the processes involved in its transport to the surface and how it evolves on the way. Isotope geochemistry, in particular, provides information on the evolutionary processes of fractional crystallization, crustal assimilation and magma supply. I have applied these techniques to volcanic systems in Ecuador and California.

The Chalupas caldera, located in the Ecuadorian Andes was formed approximately 200,000 years ago by the eruption of over 200 cubic kilometers of ash and pumice into the Interandean valley. The eruptive deposits from Chalupas are mined in the Interandean Valley and large blocks of volcanic tuff are used for building.

The Clear Lake volcanic system is located in the eastern Coast Ranges of Califonia about 135 km north of San Francisco. The volcanic system has been active over the past 2 million years and is now the site of the Geysers Geothermal Field, the largest producing geothermal field in the world.

Available student projects

• Volcanism of the Mexican Volcanic Belt

• Magma mixing textures at Chaos Crags, Lassen Volcanic National Park

Professional Associations ::

American Geophysical Union

Geological Society of America

National Association of Geoscience Teachers

California Mineral Education Foundation