Context: A sawmill or lumber mill is a facility where logs are cut into lumber. Prior to the invention of the sawmill, boards were rived (split) and planed, or more often sawn by two men with a whipsaw, one above and another in a saw pit below. The earliest known mechanical mill is the Hierapolis sawmill, a Roman water-powered stone mill at Hierapolis, Asia Minor dating back to the 3rd century AD. Other water-powered mills followed and by the 11th century they were widespread in Spain and North Africa, the Middle East and Central Asia, and in the next few centuries, spread across Europe. The circular motion of the wheel was converted to a reciprocating motion at the saw blade. Generally, only the saw was powered, and the logs had to be loaded and moved by hand. An early improvement was the development of a movable carriage, also water powered, to move the log steadily through the saw blade., A fall line (or fall zone) is the geomorphologic break that demarcates the border between an upland region of relatively hard crystalline basement rock and a coastal plain of softer sedimentary rock. A fall line is typically prominent when crossed by a river, for there will often be rapids or waterfalls. Many times a fall line will recede upstream as the river cuts out the uphill dense material, often forming c-shaped waterfalls. Because of these features riverboats typically cannot travel any farther inland without portaging, unless locks are built there. On the other hand, the rapid change in elevation of the water, and the resulting energy release, makes the fall line a good location for water mills, grist mills, and sawmills. Because of the need for a river port leading to the ocean, and a ready supply of water power, settlements often develop where rivers cross a fall line., A coastal plain is flat, low-lying land adjacent to a seacoast. One of the world's largest coastal plains is located in eastern South America. The Gulf Coastal Plain of North America extends northwards from the Gulf of Mexico along the Lower Mississippi River to the Ohio River, which is a distance of about ., Tsenacommacah ( pronounced / snkmk / in English ; `` densely inhabited land '' ; also written Tscenocomoco , Tsenacomoco , Tenakomakah , Attanoughkomouck , and Attan - Akamik ) is the name given by the Powhatan people to their native homeland , the area encompassing all of Tidewater Virginia and parts of the Eastern Shore . More precisely , its boundaries spanned 100 miles ( 160 km ) by 100 miles ( 160 km ) from near the south side of the mouth of the James River all the way north to the south end of the Potomac River and from the Eastern Shore west to about the fall line of the rivers . The Powhatan were part of a powerful Chiefdom of Virginia Indian tribes , also known as the Powhatan Confederacy , that spoke an Algonquian language . By the time the English arrived in Tsenacommacah , the Powhatan Indian Chiefdom included over 30 tribes . Each tribe had its own name and chief ( werowance / weroance or weroansqua if female ) , and the chiefdom as a whole was ruled by a paramount chief ( mamanatowick ) named Wahunsenacawh , or more popularly Chief Powhatan . The Eastern Shore Indians , the Accawmacke , who numbered around 2000 , paid nominal tribute to the Powhatan , but enjoyed a large degree of semi-autonomy under their own paramount chief , Debedeavon ( `` the Laughing King '' ) ., Subject: tsenacommacah, Relation: continent, Options: (A) asia (B) europe (C) north america (D) south america
Output: north america