How to find six grid reference on the map?

The intersecting lines drawn on maps and globes are? ... What are the important lines on a globe or map? ... The problem is that a map is an attempt to fit a representation of the Earth's surface, ...What is a straight line that intersects a curve?

Sequoia national park  /  inyo national forest, california, u.s. mount whitney is the tallest mountain in california, as well as the highest summit in the contiguous united states and thesierra nevada—with an elevation of 14,505 feet (4,421 m).