astronomy

Jan Tullis

Jan Tullis is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Jan Tullis rather than just read about it. In short: Julia Ann “Jan” Tullis was an American structural geologist and emerita Professor at Brown University. Tullis is known for her work in structural geology, especially for her experimental work in deformation mechanisms, microstructures, and rheology of crustal rocks.

Key takeaways

Jan Tullis belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Jan Tullis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Jan Tullis from memory before moving on to harder problems.

Reference excerpt

Julia Ann “Jan” Tullis was an American structural geologist and emerita Professor at Brown University. Tullis is known for her work in structural geology, especially for her experimental work in deformation mechanisms, microstructures, and rheology of crustal rocks.

Education and career Tullis graduated Magna Cum Laude with distinction from Carleton College in June 1965, earning her A.B. in Geology. Following this she completed her PhD at the University of California, Los Angeles in 1971 with a thesis on experimental rock deformation. Tullis became a research assistant at Brown University while editing her dissertation in 1970. Later, Tullis was named a Research Assistant Professor in 1971, Associate Professor in 1979, and a full Professor in 1989. She transitioned to Professor Emerita in 2013 but continued with undergraduate teaching and advising right up to her death in September 2024.

Research Tullis' research involved experimental investigations of the deformation mechanisms, microstructures and rheology of crustal rocks using constant strain-rate Griggs-type solid medium apparatus including adaptations for molten salt assemblies. Her two major goals were to enable more accurate inferences concerning the thermomechanical history of naturally deformed rocks based on their preserved microstructures and crystallographic preferred orientations, and to provide mechanical data and flow laws to enable more accurate modeling of crustal deformation under various conditions. Experiments were conducted on monophase and polyphase aggregates, both natural and synthetic, over a wide range of pressure and temperature conditions equivalent to those from the shallow to the deep crust, and involving varying controlled water contents. She and her students and other collaborators documented grain-scale Deformation mechanisms from brittle fracturing to cataclastic flow to dislocation creep and melt or fluid-enhanced diffusion creep. These experiments investigated the role of phase distribution and contiguity in the progressive deformation of polyphase aggregates, and documented a number of processes resulting in strain weakening and localization, such as in mylonite zones. Tullis' work with Renee Heilbronner examined fabric evolution during progressive shearing and static annealing.

Selected publications Microstructures and preferred orientations of experimentally deformed quartzite: Tullis, Christie, and Griggs (1973) Experimental deformation of dry westerly granite: Tullis and Yund (1977) Hydrolytic weakening of experimentally deformed westerly granite and Hale albite rock: Tullis and Yund (1980) Significance and petrogenesis of mylonitic rocks: Tullis, Snoke, and Todd (1982) Flow strengths of quartz aggregates: grain size and pressure effects due to hydrolytic weakening: Kronenberg and Tullis (1984) Dynamic recrystallization of feldspar: a mechanism for ductile shear zone formation: Tullis and Yund (1985) Ductile shear zone from brittle precursors in feldspathic rocks: the role of dynamic recrystallization: Tullis, Dell Angelo, and Tund (1990) Dislocation creep regimes in quartz aggregates: Hirth and Tullis (1992) Chapter 4 The Brittle-Ductile transition in feldspar aggregates: an experimental study: Tullis and Yund (1992) A flow law for dislocation creep of quartz aggregates determined with the molten salt cell: Gleason and Tullis (1995) Deformation-enhanced fluid distribution in feldspar aggregates and implications for ductile shear zones: Tullis, Yund, and Farver (1996) Textural and mechanical evolution with progressive strain in experimentally deformed aplite: Dell Angelo and Tullis (1996) A recrystallized grain size piezometer for experimentally deformed feldspar aggregates: Post and Tullis (1999) Weakening and strain localization produced by syn-deformational reaction of plagioclase: Stunitz and Tullis(2001) The effect of static annealing on microstructures and crystallography preferred orientations of quartzites experimentally deformed in axial compression and shear: Heilbronner and Tullis (2002) Reaction-induced weakening of plagioclase-olivine composites: DeRonde, Stunitz, and Tullis (2005) Dauphiné twinning as evidence for an impact origin of preferred orientation in quartzite: An example from Vredefort, South Africa: Holyoke and Tullis (2005) Effect of water on the dislocation creep microstructure and flow stress of quartz and implications for the recrystallized grain size piezometer: Stipp and Tullis (2006) Mechanisms of weak phase interconnection and the effects of phase strength contrast on fabric development: Holyoke and Tullis (2006) Evolution of c axis pole figures and grain size during dynamic recrystallization: Results from experimentally sheared quartzite: Heilbronner and Tullis (2006) Effect of aqueous and carbonic fluids on the dislocation creep strength of quartz: Chernak, Hirth, Selverstone, and Tullis (2009)

Awards and honors Fellow, Mineralogical Society of America (1985) Fellow, Geological Society of America (1995) Phil Bray Award for Teaching Excellences in Physical Sciences (1995) Fellow, American Geophysical Union (1996) Association for Women Geoscientists Outstanding Educator Award (1998) Harriet W. Sheridan Award for Distinguished Contribution to Teaching and Learning (2000) Karen Romer Award for Undergraduate Advising and Mentoring (2004) Structural Geology & Tectonics Career Contribution Award (2005)

References

Illustrations

Worked examples

Example 1 — a first encounter with Jan Tullis

Start with the simplest possible case. Write down what Jan Tullis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Jan Tullis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Jan Tullis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Jan Tullis

In research: Jan Tullis appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Jan Tullis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Jan Tullis is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1943 births, American women geologists, Brown University faculty, so understanding it makes those chapters shorter.
In everyday life: Look for Jan Tullis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Jan Tullis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Jan Tullis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Jan Tullis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jan Tullis in simple terms?

Why does Jan Tullis matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Jan Tullis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Jan Tullis.