Cavity and solid walls. 1  A cavity wall is made up of two walls with a gap in between, known as the cavity; the outer leaf is usually made of brick, and the inner layer of brick or concrete block.  A solid wall has no cavity; each wall is a single solid wall, usually made of brick or stone.
A cladogram (from Greek clados branch and gramma character) is a diagram used in cladistics which shows relations among organisms.
The term cladistics comes from the word clade. A clade is a group of organisms that includes an ancestor species and all of its descendants. A diagram showing evolutionary relationships within one or more clades is called a cladogram. A clade is a relative concept. cladogram shows how species may be related by descent from a common ancestor. A classification of organisms on the basis of such relationships is called a phylogenetic classification. A phylogenetic classification involves placing organisms in a clade with their common ancestor. Consider the cladogram in Figure below.