Changes

Sand grain size has a wide range of scale, from very coarse sand until very find sand. For the grain size measurement, its use a formula proposed by Krumbein in 1934, is based on the following relationship :

Sand grain size has a wide range of scale, from very coarse sand until very find sand. For the grain size measurement, its use a formula proposed by Krumbein in 1934, is based on the following relationship :

:Ф = -log2 d

:<math>\phi = -\log 2d</math>

Where Ф (phi) size and d is the grain diameter in milimeters. For example, a grain 4 mm in diameter has a phi size of -2, which is the power required to raise the base (2) of the logarithm to 4 (i.e. 22)

Where Ф (phi) size and d is the grain diameter in milimeters. For example, a grain 4 mm in diameter has a phi size of -2, which is the power required to raise the base (2) of the logarithm to 4 (i.e. 22)

Fig 1. Udden-Wentworth Grain Scale (Sand scale)

Fig 1. Udden-Wentworth Grain Scale (Sand scale)