Final answer:
Passive margins are produced after periods of tectonic activity, known as orogenies, have ceased, leading to a stable environment characterized by deposition of sediments such as limestones. The Valley and Ridge Province and Morocco's geologic history exemplify this transition from active to passive margins.
Step-by-step explanation:
Passive margins are typically associated with areas of little to no tectonic activity. Over geologic time, passive margins are produced after the cessation of orogenies, which are periods of intense tectonic activity associated with mountain building. For example, the Valley and Ridge Province in northwestern New Jersey displays sedimentary deposits derived from two such tectonic events, the Taconic Orogeny and the Acadian Orogeny. After these orogenies, a transition back to a stable passive margin occurs, which is characterized by the sequence of fine sediment deposition transitioning to shallow marine carbonates such as limestones. An area's geologic history, including periods of tectonic activity like the Hercynian orogeny in Morocco's past, is recorded in its rock formations and structures.
Looking for certain types of sedimentary rocks can help decipher the tectonic history of an area. For instance, limestones are indicative of passive margin conditions, while sandstones, shales, and conglomerates suggest previous active margin environments with uplift and subsequent erosion. In the case of Morocco, the history of passive margin formation is evidenced by the deposition of marine sediments as the Atlantic Ocean formed due to the rifting of Pangaea.