One unbroken chalk line marked marked midfield?

1. I'm not sure about today's marking substance, but for many years, in the old days, it was nothing more than POWDERED CHALK, which I think is Calcium Carbonate. Today, some are using synthetic...

The longest lines on the pitch are called the sidelines; The lines adjacent to each end of these are called the backlines or baselines; The line half way from these lines is called the half way...

These allow diagonal crossing. All vehicular traffic stops, and pedestrians are allowed to cross left, right, or diagonally across the intersection.

The Appalachian Mountains

The H stands for high pressure side and the L stands for low pressure side.