New England Travels

Formed near the South Pole, the Boston area is heading west, says Geology's Fr. Skehan in new article

By Mark Sullivan
Contributing Writer

The site Boston College calls home has done some traveling over the years, according to Prof. Emeritus James Skehan, SJ (Geology), and its journey isn't over yet. Once part of the West African subcontinent located near the South Pole, he said, Chestnut Hill may, in 200 million years or so, lie where the West Coast is now.

Fr. Skehan, director emeritus of the Weston Observatory, offers these and other insights into the geological features of the Boston area in a paper he recently co-authored, "Late Proterozoic to Cambrian Evolution of the Boston Avalon Terrane." The paper, published in the Geological Association of Canada book Current Perspectives in the Appalachian-Caledonian Orogen , contains revealing details about the ground upon which Boston College rests.

Prof. Emeritus James Skehan, SJ (Geology)-"The data is in the rocks. I don't care for puzzles in and of themselves, but the puzzle of the Earth is of consuming interest." (Photo by Gary Gilbert)
Mapping multi-million year changes in the Earth's face is a passion for Fr. Skehan, who compares his fascination with deciphering the geologic record with that of an archaeologist translating the hieroglyphics on the Rosetta Stone.

"The data is in the rocks," said Fr. Skehan. "I don't care for puzzles in and of themselves, but the puzzle of the Earth is of consuming interest."

Fr. Skehan's paper suggests that a large section of eastern North America, including the environs of Boston, formed between 500 million and 750 million years ago as a volcanic chain off the coasts of what are now the West African and South American subcontinents, then clustered near the South Pole. The Avalon terrane - the geological micro-continent upon which Boston lies - drifted over time, joining the North American land mass in a continental collision 400 million years ago, Fr. Skehan said.

Fr. Skehan's research into the Avalon terrane provides a glimpse into the striking features of the Chestnut Hill area. A geologic fault runs below the O'Neill Library and the Commonwealth Avenue parking garage, he said, which explains why the Middle Campus is higher than the Lower Campus. Left like a scar when continents broke apart some 200 million years ago, the bluff is a long dormant fault zone, he said, and the chance of an earthquake beneath the library is "minuscule."

Boston College's gothic architecture, Fr. Skehan added, is even more distinctive when one considers the source of the construction materials. The Roxbury puddingstone used to build Gasson, Devlin and St. Mary's halls originated as gravel washed down from volcanoes at the South Pole between million 550 and 600 million years ago, he said.

The slow-motion continental migration is still going on, Fr. Skehan noted. North America and Europe continue to drift away from each other, as do South America and Africa, at a rate of three-quarters of an inch per year. If the process continues, in 200 million years the Atlantic Ocean will be much larger and the Pacific much smaller, he said. Chestnut Hill would wind up at the present site of the West Coast, while land to the west of the active San Andreas Fault in California will be pushed to the northwest.

"Los Angeles might be subducted under Alaska and recycled through the volcanoes," Fr. Skehan mused.

Fr. Skehan is continuing his research into the geological aspects of Massachusetts, having nearly completed a book which will map rock-hunting routes along the major roads of the state. He regards his latest work as reflecting a career in which science and religious faith have complemented one another.

"If you look at a beautiful sunset, or how mountains are formed, or observe how continents move," he said, "you can view it either as science or as God speaking to you, or both. I do both. What I do as a scientist is no different from what I do listening to the cosmic word of God."

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