Howard Jerz, age 9, of Harvey, Ill., for his question:

Is it true that the earth's surface is still changing?

Great changes happened in the crust of North America only a few years ago. A great slab of l2,000 square miles was lifted up 7.5 feet. Another slab three times bigger    dropped about    5 feet lower. These changes Were caused by the disastrous earthquake that stunned Alaska on March 27, l964. The earth's crust changes all the time, but usually at a slow pace which We don't notice. The earth is billions of years old and her wrinkled surface has never stopped changing. Through the ages, mountains slowly rise and wear down to become gentle hills. Rivers cut gorges and seeping water digs underground caves that collapse. Volcanos spew layers of lava and dusty debris adds new layers on the ground. Ice Ages bring monstrous glaciers that scrape and gouge the surface crust. sometimes the seas invade the land and leave behind herd, dry layers of silt.