* Astronomy

Within Texas, credible proposals have been made for the extraterrestrial impact origin of five geological structures. Convincing cases have been made for three of these structures, i.e. Marquez structure (Leon County), Odessa crater (Ector County), and Sierra Madera (Pecos County), of being of impact origin (Gibson 1990; Littlefield et al. 2007; Howard et al. 1972; Wilshire et al. 1968; Wong 2001). Another proposed Texas impact structure, the Wilbarger structure in Wilbarger County, has been discredited by detailed field research (Nelson 2006). The origin of the last of these structures, the Hico structure, which lies in Hamilton-Erath County, remains an unresolved mystery.
The Hico structure is a circular disturbance that is developed in Lower Cretaceous strata, upper Glen Rose, Paluxy, and lower Walnut formations about 3 km (1.8 miles) north of Hico, Texas and 32.085 degrees north latitude and 98.0342 degrees west longitude.


Expand (139kb, 706 x 1081)

Read more (1.1mb, PDF)