From Las Vegas, travel north on I-15, toward Saint George, Utah. Take the exit marked "Valley of Fire/Lake Mead National Recreational Area in Moapa.
This formation is called Seven Sisters. It is visible from the main road on the scenic drive through the park. There are picnic tables at this stop. Don't skip the side trip up to Mouse's Tank and White Domes. It is so worth it! Gas up and get supplies at the Moapa Paiute Travel Plaza when you exit the freeway. There is nothing to eat in the park or at the Visitor's Center.