![]() ![]() The oldest rocks in Texas date from the Precambrian, specifically the Mesoproterozoic and are about 1,600 million years old, and mark the southern limit of the North American craton. The zone of deformation known as the Ouachitas marks a zone of weakness that was exploited when the Gulf of Mexico opened about 165 Ma, in Jurassic time. The Marathon- Ouachita- Appalachian- Variscan cordillera, which stretched through central Texas, around Arkansas, up through the Appalachian Mountains and eventually into eastern Europe, occurred when the supercontinents Pangea and Laurussia collided to form Pangea in the late Paleozoic ≈300 Ma. To the north of the DFW Metroplex, the roots of the mountains can be identified in SE Oklahoma as the Arbuckle mountains, heavily eroded from the original vast mountain range. In west Texas near Marathon, the mountain range appears on the surface, and is known as the Marathon Uplift. Although the Ouachita Mountain roots are not visible in the DFW Metroplex since they are buried, they can still be recognized through boreholes and other data. These ancient mountains were reduced by erosion and rifting associated with the opening of the Gulf of Mexico in the Jurassic and then were buried beneath younger Cretaceous sediments. Ancient folded mountains formed by the Ouachita orogeny existed in the eastern part of the Metroplex 300 million years ago. Sediments older than Cretaceous can only be found at the surface in the extreme western part of the DFW Metroplex, in the area around Weatherford, Texas. The geology of the DFW Metroplex consists of gently tilted sediments of mostly Cretaceous age, which also obscures a much older geologic record. They are rendered piecewise-linearly, byĭefault using segments = 48.Structural features located within East and Central Texas Structural and tectonic history of the DFW Metroplex Interval \(\) to itself, and each is rescaled so that its endpoints Not (yet) used in ggalluvial, but several alternative curves are available.Įach is encoded as a continuous, increasing, bijective function from the unit Quick to render and clear to read, but users may prefer plots that useĪ variety of such options are documented at, e.g., this easing functions cheat sheet and this blog post by Jeffrey Shaffer. Parameterized by the relative location of the knot ( knot.pos). borders().Īdditional arguments passed to ggplot2::layer().īy default, geom_alluvium() and geom_flow() render flows between lodes asįilled regions between parallel x-splines. That define both data and aesthetics and shouldn't inherit behaviour from If FALSE, overrides the default aesthetics, It can also be a named logical vector to finely select the aesthetics to ![]() NA, the default, includes if any aesthetics are mapped.įALSE never includes, and TRUE always includes. Should this layer be included in the legends? Plotted in grey (regardless of the color scheme). If TRUE, NA lodes constitute a separate category, If FALSE, the default, NA lodes are not included The number of segments to be used in drawing each alternativeĬurve (each curved boundary of each flow). To obtain the shape that will be scaled to fit between strata. curve_rangeįor alternative curve_types based on asymptoticįunctions, the value along the asymptote at which to truncate the function "xspline" produces approximation splines using 4 points per curve theĪlternatives produce interpolation splines between points along the graphs "cubic", "quintic", "sine", "arctangent", and "sigmoid". curve_typeĬharacter the type of curve used to produce flows.ĭefaults to "xspline" and can be alternatively set to one of "linear", The length of each flow (the default), rather than on the x scale. Logical whether to interpret knot.pos as a proportion of Strata, or (if knot.prop = FALSE) on the scale of the x direction. Proportion of the length of the x-spline, i.e. ( width/2 from its axis), either (if knot.prop = TRUE, the default) as a The horizontal distance of x-spline knots from each stratum Numeric the width of each stratum, as a proportion of theĭistance between axes. "jitter" to use position_jitter), or the result of a call to a Position adjustment, either as a string naming the adjustment The statistical transformation to use on the data A function can be createdįrom a formula (e.g. Seeįortify() for which variables will be created.Ī function will be called with a single argument, All objects will be fortified to produce a data frame. If NULL, the default, the data is inherited from the plotĭata as specified in the call to ggplot().Ī ame, or other object, will override the plotĭata. You must supply mapping if there is no plot Inherit.aes = TRUE (the default), it is combined with the default mappingĪt the top level of the plot. Set of aesthetic mappings created by aes(). ![]()
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