When this happens gasses dissolved in the magma are able to come out of solution, forming gas bubbles (the cavities) inside it. When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas bubbles and traps them inside, preserving them as holes filled with gas called vesicles.
He took them to the Argonne National Laboratory, where he was granted time on a late-model mass spectrometer. In a meeting in Wisconsin soon afterward, Patterson revealed the results of his study. The definitive age of the Earth is 4.550 billion years (give or take 70 million years). The current estimate for the age of the earth is 4.54 Â± 0.05 billion years (4.54 Ã 109 years Â± 1%).
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 lower limit (the Earth must be at least as old as any formation on it). This lower limit is at least concordant with the independently derived figure of 4.55 billion years for the Earth's actual age.