astronomy

Ulbo de Sitter

Ulbo de Sitter 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 Ulbo de Sitter rather than just read about it. In short: Lamoraal Ulbo de Sitter (6 March 1902 – 12 May 1980) was a Dutch geologist at Leiden University, where he was the founder of the school of structural geology. De Sitter was known for his research on the geology of the Alps and Pyrenees.

Key takeaways

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

Reference excerpt

Lamoraal Ulbo de Sitter (6 March 1902 – 12 May 1980) was a Dutch geologist at Leiden University, where he was the founder of the school of structural geology. De Sitter was known for his research on the geology of the Alps and Pyrenees. His father was the astronomer Willem de Sitter (1872–1934), and one of his sons was the Dutch sociologist Ulbo de Sitter (1930–2010).

Life and Works De Sitter studied geology in Switzerland and later at Leiden, where he was a pupil of geologists Karl Martin (1851–1942) and Berend George Escher (1885–1967). He finished his dissertation in 1925 and then got a job at Bataafse Petroleum Maatschappij. After some years, he returned to Leiden to become Escher's assistant. De Sitter's task was to supervise fieldwork and research in the Bergamo Alps (northern Italy). In addition to mapping geological structures, De Sitter also did experimental research on the development and origin of geological structures such as faults or folds. He worked together on these experiments with Philip Henry Kuenen, an old friend from his student days who would later become a professor at Groningen. The Second World War made research outside the Netherlands impossible for Dutch geologists. De Sitter and mining engineer W.A.J.M. van Waterschoot van der Gracht organised field studies of the subsurface of the southeastern part of the Netherlands. The students who participated were in this way excluded from forced labour for the Nazi authorities. De Sitter started a geologic research program in the Pyrenees and Cantabria (both in northern Spain) after the war. The geological surveys by the Leiden students are in some cases still used by the Spanish geologic survey. De Sitter became a professor in 1948. His further research was mainly on similarities and relations between different small-scale geologic structures (such as boudins, schistocities or parasitary folds) and large-scale structures (such as folds and thrusts up to the scale of mountain ranges). His book Structural Geology was translated into many languages and used worldwide. In his later years at Leiden, his health prevented him from doing more field research, thus reducing his motivation. His method of putting all geologic observations into one large framework would be characteristic for the Leiden school of structural geology, which was continued under Henk Zwart after De Sitter's retirement in 1968. In 1962, he became a member of the Royal Netherlands Academy of Arts and Sciences.

Selected publications De Sitter, L. U. "Diagenesis of oil-field brines." AAPG Bulletin 31.11 (1947): 2030-2040. De Sitter, Lamoraal Ulbo, and Catharina Maria de SITTER-KOOMANS. The geology of the Bergamasc Alps, Lombardia, Italy. 1949. De Sitter, Lamoraal Ulbo, and L. U. Sitter. Structural geology. New York: McGraw-Hill, 1964. Zwart, Hendrik Jan, and L. U. De Sitter. The geology of the central Pyrenees. Geologisch en mineralogisch Instituut der Rijksuniversiteit, 1979. Articles, a selection:

De Sitter, L. U. "Diagenesis of oil-field brines." AAPG Bulletin 31.11 (1947): 2030-2040. De Sitter, L. U. "Boudins and parasitic folds in relation to cleavage and folding." Geologie en Mijnbouw 20 (1958): 277-286. De Sitter, L. U. "Structural development of the Arabian Shield in Palestine." Geol. Mijnbouw 41.3 (1962): 116-124.

References

External links (in Dutch) Ulbo de Sitter Kennisinstituut Archived 2014-12-20 at the Wayback Machine

Illustrations

Worked examples

Example 1 — a first encounter with Ulbo de Sitter

Start with the simplest possible case. Write down what Ulbo de Sitter 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 Ulbo de Sitter 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 Ulbo de Sitter 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 Ulbo de Sitter

In research: Ulbo de Sitter 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 Ulbo de Sitter 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: Ulbo de Sitter is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1902 births, 1980 deaths, 20th-century Dutch geologists, so understanding it makes those chapters shorter.
In everyday life: Look for Ulbo de Sitter 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 Ulbo de Sitter in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ulbo de Sitter 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 Ulbo de Sitter out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ulbo de Sitter in simple terms?

Why does Ulbo de Sitter 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 Ulbo de Sitter?

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 Ulbo de Sitter.