Final answer:
True. The North American continent indeed consists of a coherent piece of ancient continental crust known as Laurentia. It has ancient geological features like the Canadian Shield, evidence of significant tectonic events, and was once part of the supercontinent Pangaea. The correct answer is option a.
Step-by-step explanation:
The statement that the North American continent is composed of a coherent piece of ancient continental crust is true. One prime example of this ancient crust is Laurentia, a craton that includes most of North America and Greenland and has remained largely intact since the late Proterozoic era. During the collision with Baltica, a northern craton of Europe, substantial geological formations such as the Taconic or Caledonian Mountains were created, forming part of Laurasia.
Geologically, North America boasts the Canadian Shield, which is part of the ancient cratonic core and primarily comprises rocks that predate significant geological events like the Grenville Orogeny associated with the Rodinia supercontinent. Geological features like the Manhattan schist offer evidence of North America's dynamic geological history, including major tectonic collisions evidenced by the sandstone formations in Colorado and Utah, fossil records in the northwest, and the active San Andreas fault. Moreover, this continent once joined with others to form the supercontinent Pangaea, which encompassed almost all of Earth's continental crust around 200 to 300 million years ago.