Gravel road embankments in low-lying areas. Cellular confinement systems can be used to prevent the washboarding effect. The gravel used consists of varying amount of crushed stone, sand, and "fines". Fines are silt or clay particles smaller than , which can act as a binder. Crushed stone is used because gravel with fractured faces will stay in place better than rounded river pebbles. A good gravel for a gravel road will have a higher percentage of fines than gravel used as a subbase for a paved road. This often causes problems if a gravel road is paved without adding sand and gravel
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"