Final answer:
The continental margins of the Atlantic can be either tectonically passive or active, depending on the specific location. We can determine whether an area is tectonically passive or active by examining the types of rocks found in the region and assessing the level of seismic activity. Limestone is typical of passive margins, while sandstones, shales, and conglomerates are indicative of active margins.
Step-by-step explanation:
The continental margins of the Atlantic can be either tectonically passive or active, depending on the specific location. Tectonically passive margins are characterized by relatively low levels of seismic activity and little to no mountain building. Examples of tectonically passive margins in the Atlantic include the East Coast of the United States and the coast of Brazil. On the other hand, tectonically active margins exhibit high levels of seismic activity and are associated with mountain building. Examples of tectonically active margins in the Atlantic include the western coast of South America and the coasts of western Europe and Africa.
We know whether an area is tectonically passive or active by examining various types of geologic evidence. One important piece of evidence is the type of rocks found in the region. Limestone, which is typically associated with passive margins, indicates minimal tectonic activity. On the other hand, sandstones, shales, and conglomerates, which are commonly found on active margins, suggest the presence of uplift and erosion from mountain-building processes. Additionally, seismic activity, such as the occurrence of earthquakes and volcanic activity, can provide further evidence of a region's tectonic activity.