Local shear failure occurs when the shear stresses parallel to the grain, i.e. shear stresses acting in the longitudinal-tangential (LT) or longitudinal-radial (LR) planes, exceed the shear strength of the beam. The shear strength of a wood member is difficult to quantify.
The fossils are found in sedimentary rocks such as sandstone, limestone and even coal. This type of rock tends to be in very deep layers and for this reason they are easier to house the fossils. they are formed by the melting of other rocks.
