The rocks rich in silicon and aluminum that form the upper layer of the earth's crust, which lies beneath all continental landmasses.
Examples:
"Geologists study the composition of sial to understand the formation of continents. "





"Geologists study the composition of sial to understand the formation of continents. "

"The seven continents are large landmasses on Earth. "

Each of the main continuous land-masses on the earth's surface, now generally regarded as seven in number, including their related islands, continental shelves etc.
"Students in geography class learn about the seven continents: Asia, Africa, North America, South America, Europe, Australia, and Antarctica. "

"My new classmate is a continental, having recently moved here from Europe. "