So, the dinosaurs had the technology to make glass? Did the asteroid strike a glass bottle factory?
"PEEKSKILL, N.Y. — Twenty-five years after a meteorite tore through the trunk of a teenager’s Chevy Malibu Classic in this northern Westchester County city..."
Find a large slab of sandstone. Arrange for an asteroid to strike it. During the resulting explosion, the sandstone will be shattered and melted, and thrown into the sky. The molten ejecta will become glass spheres of various sizes and will fall to the earth. It’s so easy that even a Cave Man can do it.