In the figure, triangle ABC is isosceles with $AB=AC$. Line segment DE is parallel to line segment BC, with point D on AB and point E on AC. If the measure of $\angle ADE$ is $70^{\circ }$, what is the measure of $\angle BAC$?

(Note: A diagram would show triangle ABC with a line segment DE parallel to BC, where D is on AB and E is on AC. $\angle ADE$ is labeled $70^{\circ }$.)