Soil mechanics necessary to run water through the sieves to wash the coarse particles and clods through. A variety of sieve sizes are available. The boundary between sand and silt is arbitrary. According to the Unified Soil Classification System, a #4 sieve (4 openings per inch) having 4.75mm opening size separates sand from gravel and a #200 sieve with an 0.075 mm opening separates sand from silt and clay. According to the British standard, 0.063 mm is the boundary between sand and silt, and 2 mm is the boundary between sand and gravel. The classification of fine-grained soils, i.e., soils that are
Mike Gravel run for president. Gravel favors abortion rights. During the 2008 campaign, Gravel was a strong supporter of LGBT rights. He supported same-sex marriage and opposed the Defense of Marriage Act and the U.S. military's "don't ask, don't tell" policy. He wrote in 2008 that "depriving gays and lesbians of equal rights is immoral." Gravel is a critic of what he terms American imperialism. Gravel firmly opposes U.S. military action against Iran and Syria. He voiced opposition to the Guantanamo Bay detention camp, the Military Commissions Act of 2006, the use of torture, indefinite detention, and what he called "flagrant ignorance"