Taxonomy is the science of classifying organisms. The system currently used by taxonomists is called the Linnaean taxonomic system, in honor of Swedish biologist Carolus Linnaeus (1707 â 1778). The Linnaean system breaks down organisms into seven major divisions, called taxa (singular: taxon).
When used by the Chinese to protect their land, this section of the wall has had many guards to defend China's capita, Beijing. Made of stone and bricks from the hills, this portion of the Great Wall is 7.8 meters (25.6 ft) high and 5 meters (16.4 ft) wide.
The first step in building a block wall is pouring a concrete footing for the blocks to rest on. The footing has to be below frost line and as level as you can make it. For a foundation wall with 7 courses (rows) of block, the footing was 30 inches below grade, 24 inches wide and 12 inches deep. Footings require a lot of concrete, so if you're building long walls, it might be a good idea to hire a contractor to pour the footings.