(antiform and synform), the terms anticline and syncline are used in description of the stratigraphic significance of the fold. These phrases can be used in conjunction with one another to describe the geometric aspects of the shape and direction of the fold. In addition, folds can be referred to as either symmetrical or asymmetrical. When a group of folds, whose axial planes are found to be perpendicular to the plane representing the enveloping surface of the folds (plane drawn tangential to the folds), the folds are considered symmetrical. When this is not the case, the folds are considered asymmetrical, and the asymmetry of these folds will vary systematically across the axial surfaces of the folds. Vergence can be used to, not only give an overall idea of the symmetry (or asymmetry) of a fold, but in the common case of asymmetric folds, it can be used to record the previously mentioned systematic variation of asymmetry of folds. This is very important to the use of vergence in the field for geologists when determining the micro-to-macro components of an area. Uses in Geology One of the main applications of vergence in geology is the tool it provides geologists to describe the geometries of folds on a small-scale. Vergence, as well as the application of the facing of a fold, can assist geologists in classifying a fold in terms of its style (antiform or synform), as well as classifying it as a anticline or syncline, which holds stratigraphic significance. One of the most important uses of vergence is that it gives geologists a sense of the geometric property of symmetry in folds. In the case of asymmetric folds, vergence can be observed and recorded in structures known as fold pairs. Fold pairs help illustrate the angular relationship of the bedding and cleavage of the fold. They can be 'S-shaped', in which they are termed sinistral, or they can be 'Z-shaped', in which they are known as dextral. The conventional use of the terms sinistral and dextral are used to describe vergence when the vantage point of observation is from above, or the observer is looking down on the fold. Vergence, similarly to fold pairs, is sometimes classified as sinistral or dextral. This is because of the relationship between vergence and rotation, as in its definition, vergence is used to determine the direction of rotation of the upper-component of a fold. Vergence can