Weathering breaks down and loosens the surface minerals of rock so they can be transported away by agents of erosion such as water, wind and ice. There are two types of weathering: mechanical and chemical. Mechanical weathering is the disintegration of rock into smaller and smaller fragments. Frost action is an effective form of mechanical weathering. When water trickles down into fractures and pores of rock, then freezes, its volume increases by almost 10 percent.
(July 2002) Despite the fact that sub-Saharan Africa contains only about 11 percent of the Earth's population, the region is the world's epicenter of HIV/AIDS. The numbers are daunting. Adult HIV prevalence is 1.2 percent worldwide (0.6 percent in North America), but it is 9.0 percent in sub-Saharan Africa.
Philippines has fastest growing HIV infections in Asia â UN. The Philippines has the fastest growing number of HIV infections in Asia, a report by the United Nations and the government showed Tuesday. The nation saw a 140 percent increase in new cases from 2010 to 2016, even though the annual number of new infections in Asia-Pacific declined by 13 percent over the same period, according to the report. âThe Philippines has a small window of opportunity to act now and stop a major HIV epidemic from taking hold,â Eamonn Murphy, director of UNAIDS Regional Support Team said in a statement.