The C horizon is below the A and B horizons of most soils. It consists of materials that were little altered by the soil-forming processes, though the materials may be modified by weathering. Below the C horizon in some soils is an R horizon of consolidated bedrock, such as limestone, shale, or sandstone.
Ultrabooks Guide. If you want one of the most portable computers on the market, consider getting an Ultrabook, a new kind of super-thin, ultra-light laptop that wakes from sleep quickly and offers a compelling Windows 8 experience.
Buying Guide and Advice. A Chromebook is a laptop of a different breed. Instead of Windows 10 or macOS, Chromebooks run Google's Chrome OS. These machines are designed to be used primarily while connected to the Internet, with most applications and documents living in the cloud. These machines have done quite well in the education market, but their appeal has broadened.