I've never seen the construction before, except in Spanish for dialogue and Toni Morrison uses a variaton in Beloved, ";—" for denoting a strong pause (well that's we decided in my English class).
How does Henry Adams use ":—"? Is this grammatically correct? How can I incorporate this in my own sentences?
"Among senses, smell was the strongest:—the smell of hot pine-woods and sweet-fern in the scorching summer noon; of new-mown hay; of ploughed earth" - Henry Adams in The Education of Henry Adams