Some period references to leggings:
"On their legs they have Indian boots, or leggings, made of coarse woolen cloth, that either are wrapped around loosely and tied with garters, or are laced upon the outside, and always come better than half way up the thigh: these are a great defence and preservative, not only against the bite of serpents and poisonous insects, but likewise against the scratches of thorns, briars, scrubby bushes and underwood, with which this whole country is infested and overspread."
J.F.D. Smyth, Tour In The United States of America, 1784.
"Above the moccasin all the Indians wear what are called leggings, which reach from the instep to the middle of the thigh. They are commonly made of blue or scarlet cloth..." [in the 18th century, "cloth" meant wool 99% of the time]
Isaac Weld, Travels Through the States Of North America, 1799.
"Leggers, leggins, or Indian spatterdashes, are usually made of frieze or other coarse woolen cloth;"
Captain John Knox, Historical Journal, 1757.
"The Indians, who have any dealings with the English or American traders, and all of them have that live in the neighborhood, and to the east of the Mississippi, and in the neighborhood of the great lakes to the north-west, have now totally laid aside the use of furs and skins in their dress, except for their shoes or moccasins, and sometimes for their legging, as they find they can exchange them to advantage for blankets and woolen cloths, &C. which they consider likewise as much more agreeable-and commodious materials for wearing apparel."
Isaac Weld, Travels Through the States of North America, 1799.
"People that travel much in the Woods wear leggins of coarse wollen cloth..."
Nicholas Cresswell, June 1776
Although memories written down decades after the fact are suspect, here's one for leather leggings:
"Declarant states that he was then stationed at Fort Pitt, the place aforesaid. Declarant states that in obedience to the order of his said Captain Brady, he proceeded to tan his thighs and legs with wild cherry and white oak bark and to equip himself after the following manner, to Wit, a breechcloth, leather legging, moccasins and a cap made out of a racoon skin, with the feathers of a hawk, painted after the manner of an Indian warrior. His face was painted red, with three black stripes across his cheeks, which was a signification of war. Declarant states that Captain Brady's company was about sixty-four in number, all painted after the manner aforesaid."
George Roush, 19th Century Pension Papers. Describing His Clothing In 1777.
Mario