which generally included all the other features plus more food storage areas, water wells, more terraces, ramparts, palisades, fighting stages, outpost stages, underground dug-posts, mountain or hill summit areas called "tihi", defended by more multiple wall palisades with underground communication passages, escape passages, elaborate traditionally carved entrance ways, and artistically carved main posts. An important feature of pā that set them apart from British forts was their incorporation of food storage pits; some pā were built exclusively to safely store food. Pā locations include volcanoes, spurs, headlands, ridges, peninsulas and small islands, including artificial islands. Standard features included a community well for long term supply of water, designated waste areas, an outpost or an elevated stage on a summit on which a pahu would be slung on a frame that when struck would alarm the residents of an attack. The pahu was a large oblong piece of wood with a groove in the middle. A heavy piece of wood was struck from side to side of the groove to sound the alarm. The whare (a Māori dwelling place or hut) of the rangatira and ariki (chiefs) were often built on the summit with a weapons storage. In the 17th and 18th centuries the taiaha was the most common weapon. The chief's stronghold on the summit could be bigger than a normal whare, some measuring 4.5 meters x 4 meters. Artifacts Pā excavated in Northland have provided numerous clues to Māori tool and weapon manufacturing, including the manufacturing of obsidian (volcanic glass), chert and argillite basalt, flakes, pounamu chisels, adzes, bone and ivory weapons, and an abundance of various hammer tools which had accumulated over hundreds of years. Chert, a fine-grained, easily worked stone, familiar to Māori from its extensive use in Polynesia, was the most commonly used stone, with thousands of pieces being found in some Northland digs. Chips or flakes of chert were used as drills for pā construction, and for the making process of other industrial tools like Polynesian fish hooks. Another find in Northland pā studies was the use of what Māori call "kokowai", or red ochre, a red dye made from red iron or aluminium oxides, which is finely ground, then mixed with an oily substance like fish oil or a plant resin. Māori used the chemical compound to keep insects away in pā built in more hazardous platforms in war. The compound is still widely