PAGB 



PREFACE 19 



THE CAMBRIAN AND ORDOVICIAN DEPOSITS OP MARYLAND. BY 



R. S. BASSLEB 21 



INTRODUCTION 23 



THE PHYSIOGRAPHY 23 



THE GEOLOGY 24 



HISTORICAL REVIEW 25 



BIBLIOGRAPHY 34 



PALEOGEOGRAPHY OF THE CAMBRIAN AND ORDOVICIAN 45 



STRATIGRAPHIC AND PALEONTOLOGIC CHARACTERISTICS 50 



CAMBRIAN SILICEOUS FORMATIONS 52 



The London Formation 53 



The Weverton Sandstone 54 



The Harpers Shale 57 



The Antietam Sandstone 58 



CAMBRIAN-ORDOVICIAN LIMESTONES 60 



The Tomstown Limestone 61 



Topography 61 



Lithologic Characters 62 



Residual Products 63 



Economic Features 64 



Areal Distribution 65 



Thickness 66 



Age and Correlation 66 



The Waynesboro Formation 66 



Name and Synonymy 67 



Lithologic Character and Thickness 68 



Topographic Form 69 



Tomstown Waynesboro Boundary 69 



Areal Distribution 70 



Economic Features V 1 



Age and Correlation 71 



The ElbrooTc Formation 72 



Lithologic Character and Thickness 72 



Areal Distribution 72 



Topographic Form and Residual Products 73 



Age and Correlation 74 



The Conococheague Limestone 74 



Lithologic Character and Thickness 76 



Topography 81 



Areal Distribution 81 



Age and Correlation 82 



Cryptozoon Reefs 83 



Edgewise Conglomerate 86 



