1 For subsidence caused by sudden collapse of the ground to form sinkholes, several measures can be taken. 2  First, geologists can make maps of areas known to be underlain by rocks like limestone, gypsum, or salt, that are susceptible to dissolution by fluids.
The Navajos used bows and arrows, spears, clubs, tomahawks, knives and sticks among their tools and weapons. Beyond these, they also used bolas and... The Navajos used bows and arrows, spears, clubs, tomahawks, knives and sticks among their tools and weapons. Beyond these, they also used bolas and blowguns. The Navajos employed the use of several tools and weapons:Bows and arrows were used by Native Americans to defend themselves, and sometimes for fishing. They also used them for hunting animals like bison.When fighting against European explorers, Native Americans used spears.
The Navajo name for the area is Tse Bii' Ndzisgaii, which means 'valley of the rocks.'. Monument Valley's isolated rock formations are eroded remains of their Rocky Mountain ancestors, formed by sandstone deposits and geologic uplift and then shaped by wind and water. Three main layers of Organ Rock shale, de Chelly sandstone, and Moenkopi shale are visible in many of the buttes.