earth science

Rocky Butte

Rocky Butte is a earth science 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 Rocky Butte rather than just read about it. In short: Rocky Butte (previously known as Mowich Illahee and Wiberg Butte) is an extinct cinder cone butte in Portland, Oregon, United States. It is also part of the Boring Lava Field, a group of volcanic vents and lava flows throughout Oregon and Washington state.

Key takeaways

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

Reference excerpt

Rocky Butte (previously known as Mowich Illahee and Wiberg Butte) is an extinct cinder cone butte in Portland, Oregon, United States. It is also part of the Boring Lava Field, a group of volcanic vents and lava flows throughout Oregon and Washington state. The volcano erupted between 285,000 and 500,000 years ago. As part of the Boring Lava Field, Rocky Butte is considered an outlier of the Cascade Range. It was produced by the subduction of the oceanic Juan de Fuca tectonic plate under the North American tectonic plate; it is the core remnant of intrusive rock from kilate Pleistocene volcano. The butte has a calc-alkaline composition and consists of basaltic andesite with olivine phenocrysts. Historically, the butte was the home of the Rocky Butte Jail, Judson Baptist College, and Hill Military Academy, as well as an extensive Works Progress Administration construction project, Portland Bible College and a campus for the City Bible Church; at the summit of Rocky Butte there is a still functioning but decommissioned rotating airway beacon. The slopes of the butte currently support Joseph Wood Hill Park and the Rocky Butte Natural Area, which includes a wide variety of flora and fauna and supports rich forest stands. Located adjacent to Interstate 205, the butte is a popular destination for hiking, climbing, and viewing mountains from its summit viewpoint.

Geography

Rocky Butte lies in the northeast part of Portland within the city limits, in Multnomah County, part of the U. S. state of Oregon. It is one of the few smaller volcanic cones within or near Portland, along with Mount Tabor, Kelly Butte, and Powell Butte. According to the U.S. National Geodetic Survey, Rocky Butte has an elevation of 613 feet (187 m). It is surrounded on almost all sides by the Portland Delta. With a variable topography, the Portland area ranges from river valley floors to terraces reaching elevations of 400 feet (120 m). The Willamette Valley is separated within by hills reaching heights more than 1,000 feet (300 m), and it is also physically separated from the lower Columbia River valley. The Columbia River flows west from the eastern Portland region, merging with the Willamette near Portland before moving north. Tributaries for the Willamette include the Pudding, Molalla, Tualatin, Abernethy, and Clackamas Rivers, while the Washougal and Sandy Rivers mark notable tributaries for the Columbia River. The Columbia River has significantly shaped the geology of the area. Portland's climate is moderate, with long growing seasons, moderate rainfail, mild winters, and warm, dry summer seasons. The area typically does not experience frost, with more than 200 frost-free days annually. Temperature can vary widely, reaching a historic maximum of 107 °F (42 °C), though the usual July maximum is below 80 °F (27 °C), and the average minimum for January is above 32 °F (0 °C). Yearly, precipitation averages between 35 and 45 inches (89 and 114 cm) in most river valleys, with a mean of 42.04 inches (106.8 cm) from 1871 through 1952. It shows variability, however, with a historic low of 26.11 inches (66.3 cm) at Portland in 1929 and a maximum of 67.24 inches (170.8 cm) in 1882. More than 75 percent of this precipitation occurs between October and March; July and August mark the driest months with means below 1 inch (2.5 cm), while November, December, and January represent the wettest with averages greater than 6 inches (15 cm). Prevailing winds originate from the south during winter and from the northwest during the summer season, with the exception of prevailing winds at the mouth of the Columbia River Gorge, where winds predominantly move to the east. The southern winds have the highest velocities of the three, only rarely occurring with potentially destructive force.

Geology

There are a number of volcanic centers within a 20 miles (32 km) radius of Troutdale and more than 32 vents within a 13 miles (21 km) radius of Kelly Butte. Mostly small cinder cone vents, these volcanoes also include some larger lava domes from shield volcanoes at Mount Sylvania, Highland Butte, and Larch Mountain. Known as the Boring Lava Field, this cluster includes more than 80 known small vents and associated lava flows, with more volcanic deposits likely present. The Global Volcanism Program reports that the field includes somewhere between 32 and 50 shield volcanoes and cinder cones, with many vents concentrated northwest of the town of Boring. Considered an outlier of the Cascade Range, the Boring Lava Field lies about 62 miles (100 km) to the west of the major Cascade crest. It marks one of five volcanic fields along the Quaternary Cascade arc, along with Indian Heaven, Tumalo in Oregon, the Mount Bachelor chain, and Caribou in California. Like the Cascade Range, the Boring field was also generated by the subduction of the oceanic Juan de Fuca tectonic plate under the North American tectonic plate, but it has a different tectonic position, with its eruptive activity more likely related to tectonic rifting throughout the region. The Boring Lava Field has erupted material derived from hot mantle magma, and the subducting Juan de Fuca plate may be as shallow as 50 miles (80 km) in depth at their location. Many volcanic features in the Portland Basin area were destroyed by the Missoula Floods (also known as the Bretz or Ice Age Floods), which took place between 21,000 and 15,000 years ago and probably destroyed small cinder cones (including those made from tuff) and maar craters, burying them under up to 98 feet (30 m) of silt from slack water. Volcanic vents with either extensive eruptions of lava flows or volcanic plugs that filled their vents survived, including Rocky Butte, Prune Hill, and Beacon Rock. However, the upstream side of Rocky Butte was heavily eroded by the flooding.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Rocky Butte

Start with the simplest possible case. Write down what Rocky Butte claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, 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 Rocky Butte 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 Rocky Butte 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 Rocky Butte

In research: Rocky Butte appears in earth science 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 Rocky Butte 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: Rocky Butte is common in secondary-school and first-year university syllabi. It links to neighbouring topics Buttes of Oregon, Cascade Volcanoes, Cinder cones of the United States, so understanding it makes those chapters shorter.
In everyday life: Look for Rocky Butte 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 Rocky Butte in 20 minutes

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

Frequently asked questions

What is Rocky Butte in simple terms?

Why does Rocky Butte matter?

Because it connects several earth science 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 Rocky Butte?

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 Rocky Butte.