What formed this ancient, 24,000 foot tall underground rock structure? | Appalachian Geology

This video talks about structural geology under northern Virginia in response to a viewer question. Even though the Appalachians aren't very high in northern Virginia, gigantic rock structures that remain almost entirely within the ground are still present. The very tops of these structures are exposed at the ground surface to create the landscape that defines life in the Shenandoah Valley and surrounding areas. You can learn to "see" underground geologic structure by looking at patterns on the land surface. This video uses block diagrams and Microsoft Paint sketches to illustrate Appalachian Geology in the mid-Atlantic. Even though the southern and northern Appalachians have higher and more rugged landscapes, mid-Atlantic structural masses are arguably bigger, even though their presence has to be visualized!