The mass-abundance of the nine most abundant elements in the Earth's crust (see main article above) is approximately: oxygen 46%, silicon 28%, aluminum 8.2%, iron 5.6%, calcium 4.2%, sodium 2.5%, magnesium 2.4%, potassium, 2.0%, and titanium 0.61%.he mass-abundance of the nine most abundant elements in the Earth's crust (see main article above) is approximately: oxygen 46%, silicon 28%, aluminum 8.2%, iron 5.6%, calcium 4.2%, sodium 2.5%, magnesium 2.4%, potassium, 2.0%, and titanium 0.61%.
Choosing Disc Weight. Disc golf discs come in a variety of different weights. Most discs weigh between 165 and 175 grams. Some discs also come in special plastic blends designed to weigh less. The Professional Disc Golf Association regulates how heavy a disc can be based on the discs diameter.
The First Disc Golf Course. The first formal disc golf course was built in Oak Grove Park, (Pasadena, California), by Headrick in 1975 and was an instant success.By the time of his death, Ed has designed over 200 courses.