Chasma

The most prominent tectonic feature on Tethys is the globe-girdling Ithaca Chasma, which is 60 to 100 km wide, 3–4 km deep, and can be traced through at least 270° of a rough great circle (Smith et al, 1982; Moore & Ahern, 1983). […] Odysseys Tangent Chasma. A prominent chasma 60–80 km wide and at least 800 km long (90° arc), visible in 80.27, is tangent to the rim of Odysseus, trending about 10° east of north. The chasma intersects a ridge-bounded trough radial to Odysseus […] and is then lost in the zone around the North Pole that is shadowed in all of the extant images.

Venus shows clear signs of past tectonic activity in the highland regions. The deformational (tectonic) features showing^([sic – meaning show]) the results of both compressional and extensional forces. Rifting of the crust has occurred to produce relatively shallow chasmas and abundant faulting in the Aphrodite Terra and Beta Regio highlands […]

Assuming a subglacial or subaqueous setting for the ILDs [interior layered deposits], a simple tectonic control (and associated rupture of a confined aquifer) alone seems an unlikely trigger for ILD volcanism, or we should also observe ILDs in the linear chasmata, for which a tectonic setting is most likely and in which ILDs are absent. We suggest that the method of formation of the elliptical chasmata and the ILDs may be genetically related.

The near circular trough of the Artemis chasma [on Venus] has a diameter of 2100 km. The concentric features outside the chasma are attributed to normal faulting associated with lithospheric flexure similar to that occurring seaward of subduction zones on the Earth.

Thus Cornelius Gemma, Professor of Medicine in Louvain, mentions them [the aurora borealis] under the name of chasma, as appearing in Brabant on the 13th February and 28th September, 1575.

Livy (lib. xxii. cap. 1.) mentions a similar appearance among the prodigies which preceded Hannibal's entrance into Italy in the second Punic War. It was reported, says he, […] that at Falerii the Heaven seemed to be rent with a vast chasm; and that where it was opened, a great light shone forth. Such phenomena the Roman naturalists called chasmata, chasms, as we learn from Pliny [the Elder], Nat. Hist. lib. ii. cap. 26. and Seneca [the Younger], Nat. Quæst. lib. i. cap. 14.

According to the state of the atmosphere, they [the aurora borealis] differ in colour. They often put on the colour of blood, and make a most dreadful appearance. The rustic sages become prophetic, and terrify the gazing spectators with the dread of war, pestilence, and famine. This superstition was not peculiar to the northern islands; nor are these appearances of recent date. The ancients called them Chasmata, and Trabes, and Bolides, according to their forms or colours.