What has a blog in common with the old American newspaper-rocks? Oh – you don’t know what a newspaper-rock is?
The largest known collections of petroglyphs (images recorded on stone) are in eastern Utah, western United States. Archaeologists call them newspaper-rocks.
The African counterparts are the memory boards. They all serve the same purpose: Keeping the history and the tradition of a people alive. Members with a perfectly good memory are the guardians of the political continuity of the tribal community. They know everything by heart about their ancestors, events of the people’s myth, sacred places of the region where spirits and ghosts live, their names, countless proverbs, code words, songs and lyrics.
The rock or board is a memory tool for instructing the initiates, who become the next generation’s guardians of the tradition.
Right: Rock painting, Tassili[?], Algeria, North Africa (click image to enlarge) 
The symbolism is quite complex and also universal. You can find the same symbols in many other places on this planet and they are used until up to date!
They can be found on cave paintings in the south of France or in Spain or in the Tassili, Algeria. Still the Celts had them on their coins.
Left: African memory board (click to enlarge)
Matri-Blog is quite the same: it is a memory tool about humankind’s history, about its myths and symbols, about sacred places and spirits and all what is important to a social community, which is worth this name.