Boulder
Boulder names 2 different subjects across the 6 encyclopedias on this shelf. Each is set out below. 1 of them is described by more than one encyclopedia.
Boulder a loose, waterworn
Described by 2 of the 6 encyclopedias.
Aiton's Encyclopedia (1910)
a loose, waterworn, or rounded rock lying on the surface or imbedded in clay and other soils. The name is given to loose rocks lying in water courses, but especially to the rounded blocks of granite and other durable stone found in the paths of former glaciers. The theory is that they were torn from ledges of rock by streams of ice and were transported sometimes for thousands of miles. They vary greatly in size from mere pebbles to huge specimens fifteen feet in diameter. See Glacier ; Agassiz
Collier's New Encyclopedia (1921)
a large, rounded block of stone, which, whether lying loose on the surface of the ground or imbedded in the soil, is of different composition from the rocks adjacent to which it now rests, and must, therefore, have been transported from a lesser or greater distance. From the last mentioned facts, boulders are often called erratic blocks or simply erratics.
Boulder city and county-seat of Boulder co.
Collier's New Encyclopedia (1921)
city and county-seat of Boulder co., Col., on Boulder Creek and the Union Pacific and other railroads; 29 miles N. W. of Denver, the State capital. It is in a noted gold, silver, and coal mining and an agricultural and stock raising region, at the E. base of the Rocky Mountains. It received a city charter in 1882; is the seat of the State in this wood, built by Francis I., was University; and has National banks, and daily and weekly periodicals. The famous Boulder cañon is a local object of wide interest to the tourist. Pop. (1910) 9,539; (1920) 11,006.
What Has Changed in the Last Century
Aiton's 1910 definition still describes an erratic correctly, and Agassiz's ice-transport explanation has held up entirely — though geologists now know there was not one Ice Age but dozens of glacial cycles over the past 2.6 million years, the last North American and European ice sheets melting back about 11,700 years ago. Erratics are now worked backwards as evidence, their distinctive rock types traced to a parent outcrop to map the direction and speed of vanished ice. The city entry has dated far more sharply: the gold, silver and coal camps Collier's listed in 1921 are gone, and Boulder's 11,006 people have become roughly 108,000, with the State University grown to some 35,000 students. Its economy now rests on federal science — the National Institute of Standards and Technology, NOAA and the National Center for Atmospheric Research all have Boulder laboratories — rather than on mining and stock raising.
Written for this edition, 2026.