21. The dated material consisted of a piece of exterior wood containing about 30 annual growth rings . 22. The next morning, they find an growth rings . 23. Many of the tree trunks, though only an inch thick, contain 80 or more growth rings . 24. As measured by its growth rings , one fallen tree was found to be 347 years old. 25. The age of ornate box turtles has been estimated by counting growth rings for many years. 26. Broken guards show a structure of radiating calcite fibers and may also display concentric growth rings . 27. In 1914, a pine tree with 480 growth rings was found-probably the oldest known pine in Halland. 28. Without a masthead truck, water could easily seep into the circular growth rings of a wooden mast. 29. "If you look at the fast-growing trees, typically, they don't have the growth rings during their winters," 30. Cross section of the phalanx bones shows annual growth rings which may be used for determining age.
