Boulder vs Birobidzhan

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In geology, a boulder is a rock fragment with size greater than 256 millimetres (10.1 in) in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In common usage, a boulder is too large for a person to move. Smaller boulders are usually just called rocks (American English) or stones (In British English a rock is larger than a boulder). The word boulder is short for boulder stone, from Middle English bulderston or Swedish bullersten.In places covered by ice sheets during Ice Ages, such as Scandinavia, northern North America, and Siberia, glacial erratics are common. Erratics are boulders picked up by ice sheets during their advance, and deposited when they melt.

They are called "erratic" because they typically are of a different rock type than the bedrock on which they are deposited. One of them is used as the pedestal of the Bronze Horseman in Saint Petersburg, Russia. Some noted rock formations involve giant boulders exposed by erosion, such as the Devil's Marbles in Australia's Northern Territory, the Horeke basalts in New Zealand, where an entire valley contains only boulders, and The Baths on the island of Virgin Gorda in the British Virgin Islands. Boulder-sized clasts are found in some sedimentary rocks, such as coarse conglomerate and boulder clay. The climbing of large boulders is called bouldering.

Source: Wikipedia

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Birobidzhan (Russian: Биробиджа́н, IPA: [bʲɪrəbʲɪˈdʐan]; Yiddish: ביראָבידזשאַן‎, Birobidzshan) is a town and the administrative center of the Jewish Autonomous Oblast, Russia, located on the Trans-Siberian Railway, near the China-Russia border. As of the 2010 Census, its population is 75,413, and its official language is Yiddish.

Birobidzhan is named after the two largest rivers in the autonomous oblast: the Bira and the Bidzhan. The Bira, which lies to the east of the Bidzhan Valley, flows through the town. Both rivers are tributaries of the Amur.

Source: Wikipedia