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A. R. Sarid, T. A. Hurford, R. Greenberg (University of Arizona - LPL)
Cycloidal ridges are distinctive tectonic features, apparently unique to Europa. A characteristic of many cycloids is branching near a cusp (see figure). The branches are tangent to the cycloidal arc on one side, nearly perpendicular to the arc on the other, and each forms a cusp at a slightly different location. We have identified 24 branched cusps along 20 different cycloids, half with two branches and half with three. In the northern (southern) hemisphere, the tangent branching is usually to the east (west) of the cusp; this geometry has interesting correlations with the direction of crack propagation, which is known from cycloid theory (Hoppa et al., Science 285, 1999). Each branch has its own double ridge. In all clear cases, superposition of the ridges shows decreasing age toward the outside of the arc, and suggests branching may result during crack reactivation.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.