The Upper Devonian Delta Of The Appalachian Geosyncline (1914) (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: J. Barrcll? Upper Devonian Delta. 87 Art. VII. ? The Upper Devonian Delta of the Appalachian Geosyncline; by Joseph Barbell. Part II. Factors Controlling The Present Limits Of The Strata. Conteitts. Introduction and summary 87 Present extent and thickness of the Upper Devonian 88 Comparison of this restoration with other maps . 91 Influence of erosion cycles 98 Present limits dependent upon intervening baselevels.. 93 Relation of post-Ordovician erosion to original limitsxjf Devonian 95 Influence of late Paleozoic cycles of erosion 96 Degree of destruction by the pre-Newark cycle 97 The Newark erosion cycle and the qnartzite conglom-. erates 99 The Jurassic erosion cycle 1(12 The post-Jurassic erosion cycles 103 Absence of structural relations between present and orig- inal limits 105 Introduction And Summary. Toward the west and southwest the Upper Devonian delta faced the sea. The study of its strata, guided by criteria for distinguishing the modes of origin of the several formations, has led in the first part to certain conclusions. But facing the east the marginal outcrop is near the region of maximum thickness. The beveled edges of the strata, measured in thousands of feet, bear witness to a former extension toward the ancient land of Appalachia. The nature of the surface and the relations of the delta to the sea are but one half of the problem. The former extent and nature of the strata now destroyed and the relations of the delta to the old-land constitute the other half. Although Appalachia and its marginal waste plains no longer exist, we may attack these questions by inferences from the nature of the remaining strata, from the structure of the rocks beyond, and by the evidences as to the amounts of erosion whic...