How do we calculate the earths age?
The generally accepted age for the Earth and the rest of the solar system is about 4.55 billion years (plus or minus about 1%). This value is derived from several different lines of evidence. Unfortunately, the age cannot be computed directly from material that is solely from the Earth. There is evidence that energy from when the Earth was forming caused the surface to be molten. Further, the processes of erosion and crustal recycling have probably destroyed all of the earliest surface. The oldest rocks which have been found so far (on the Earth) date to about 3.8 to 3.9 billion years ago (by several radiometric dating methods). Some of these rocks are sedimentary, and include minerals which are themselves as old as 4.1 to 4.2 billion years. Rocks of this age are relatively rare, however rocks that are at least 3.5 billion years in age have been found on North America, Greenland, Australia, Africa, and Asia. While these values do not compute an age for the Earth, they do establish a lo
