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A strip in Taos County, New Mexico, eight miles long and three miles wide along New Mexico Highway 3 from U.S. Hill to Talpa, Fort Burgwin Ridge, has outcrops of Precambrian metaquartzite (1800 my bp) and cataclastic granite (1760 my bp) overlain by Mississippian limestone and Pennsylvanian fan delta sediments of the western Taos Trough. Twelve cross sections are used to demonstrate (1) Pennsylvanian syndepositional vertical movements, (2) Laramide thrusting that folded the Mississippian and Pennsylvanian rocks along splay faults to the east of the Pecos-Picuris Fault (see Fig. 40), and (3) Late Miocene to present-day normal and strike slip faulting, which is related to Rio Grande Graben rifting and appears to have reactivated earlier fault zones. The north-trending structures appear to be subsidiary to the Pecos-Picuris Fault, a major geofracture that parallels the map area to the west. / text

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Despite the recent resurgence of interest in the Chaco system, it continues to be readily apparent that the implications of the tiered-hierarchical organization of the Chaco system cannot be indiscriminately applied to the Chacoan interaction sphere. In the Limekiln Canyon locality of the Mt. Taylor District a plausible explanation for settlement and use of the landscape during the Pueblo period has been that population organization and cultural affinity were that of a late-surviving population of Archaic-like peoples who apparently only become completely absorbed into the far-reaching exchange network of the Chaco system after abandonment of the locality. This assumption is tested informally against two hypotheses that challenge such commonly accepted explanations as resource depletion for abandonment and reorganization within the Chaco region. The result is a narrative of the culture history of the locality that demonstrates the benefit of using an eclectic theoretical approach combining elements of culture history, cultural evolution and postprocessual theory. / Department of Anthropology

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The middle sandstone member of the Upper Triassic Chinle Formation in northeastern New Mexico consists of ephemeral-stream deposits adjacent to the Ancestral Rocky Mountain uplift and perennial braided-stream deposits on the plains to the east. The two fluvial systems were contemporaneous with the ephemeral rivers existing as transverse tributaries to a perennial trunk system flowing from north to south. Proximal ephemeral-stream deposits are characterized by 60-80 m thick sequences of coarse-grained sediments deposited principally by overbank sheetflooding processes. Facies associations are dominated by horizontally-stratified, medium-grained sandstone with subordinate sets of tabular-tangential and trough cross-stratified medium-grained sandstone. Streamflooding events are indicated by basal conglomeratic channelized deposits and single-story massive and trough cross-stratified channel sandstones. Uppermost portions of proximal ephemeral-stream sequences contain 0. 5 to 1. 0 m-thick units of trough cross-laminated, fine-grained sandstone and siltstone. Distal ephemeral-stream deposits are distinguished by their lenticular geometries, thicknesses of 20 to 30 m and sedimentary structures indicative of lower flow-regime streamflooding processes. Channelized conglomerates and trough cross-stratified and parallel-stratified sands~ones are capped by tabular and wedge cross-stratified, trough cross-laminated and subordinate horizontally-stratified sandstones. Facies associations in the deposits of the trunk system are comparable to those of the Platte and South Saskatchewan braided rivers (Miall, 1977). Sets and cosets of tabular-tangential or trough cross-stratified medium-grained sandstone are separated by variable thicknesses of horizontally-stratified medium-grained sandstone; these dominate 10 to 30 m-thick, sheet-like sandstones which are traceable laterally for tens of kilometers. The sheet-like sandstones are separated by equivalent or lesser thicknesses of red mudstones. Effects of the allocyclic controls of tectonics and climate are recognizable in sedimentary architectures of individual members or of the whole formation. In contrast, the effects of autocyclic controls can be recognized when internal geometries of individual members are focussed upon. The concept of base level is helpful in realizing the time dependency of controls on sedimentation because allocyclic controls determine the position of base level and base level determines which autocyclic controls operate. / M.S.