Clear weather: 8 Â°C: 2 N: 60 % 08:00: Clear weather: 10 Â°C: 2 N: 62 % 11:00: Clear weather: 16 Â°C: 2 S: 47 % 14:00: Clear weather: 16 Â°C: 2 S: 51 % 17:00: Clear weather: 12 Â°C: 1 SW: 77 % 20:00: Clear weather: 11 Â°C: 1 NE: 59 % 23:00: Clear weather: 10 Â°C: 1 NE: 49 % Tuesday 09/01: 02:00: Clear weather: 10 Â°C: 1 NE: 43 % 05:00: Almost clear: 11 Â°C: 1 E: 43 % 08:00: Clear weather: 11 Â°C: 1 NW: 47 % 11:00: Clear weather: 16 Â°C: 2 S: 44 % 14:00: Clear weather: 16 Â°C: 2 S: 59 % 17:00: Clear weather: 12 Â°C: 1 SW: 81 % 20:00: Clear weather: 12 Â°C: 1 NE: 64 % 23:00: Clear weather: 11 Â°C: 2 NE: 55 % Wednesday 10/01: 02:00: Clear weather: 10 Â°C: 2 NE: 49 % 05:00
In cylindrica l folds the crest and trough lines are parallel. to the fold axis and to each other, but in conical folds the crest and trough lines are not. parallel. Crest and trough surfaces connect the crest and trough lines on successive. horizons.
The image to the right depicts the axial plance for a simple fold. the dashed heavy line represents the fold hinge line. All the hinge lines together define the axial plane or axial surface (if it is not a planar surface). Image source USGS site: http://pubs.usgs.gov/of/2005/1428/mcinerney/. axial trace on surface: the line formed by the intersection of the axial surface and the earth's surface; i.e. the map trace of the axial surface. parallel folds 1  : also known as concentric folds. 2  thickness perpendicular to layer boundaries is maintained.