Interest in these great truths is well established now and will not be permitted to decline, because America has many scientists at work in the field of soil conservation. This work is furthered by the specialists of the U. S. Soil Conservation Service. The soil experts constantly remind the farmers, and others, that America possessed an average top “black” soil depth of nine inches when settlement was first started. They now estimate the average to be between six and seven inches. Soil conservationists hasten to point out that rocks disintegrate slowly, and that ages, not centuries, are required for the growth and decay of plants needed in the production of rich humus soil. Soil scientists do not simply call attention to dangers. They have developed dependable and salutary cultivating practices such as contour plowing of tillable soil and terracing of range land. They advise plowing stubble and cover crops under to add fertility and cohesion to the soil. Experimentation has been fruitful from the standpoint of discovering grass and legume adaptability to the different soil conditions. One phase of national security is contingent upon the effectiveness with which these practices are applied by all who work with farm, range, and forest resources. The record will prove that nearly 300,000,000 acres of land have been practically destroyed by erosion in the United States. Twice that acreage is rapidly deteriorating under the same forces. Remember, that it was only a century ago when Americans received their first rudimentary lessons in exercising a little common sense in the exploitation of resources, whether for crops, lumber, mineral, livestock, or recreational opportunities. Referring again to the status of conservation and natural philosophy in the middle nineteenth century, it should be noted that several California citizens first beheld the beauty of Yosemite in 1851. Inspired and overwhelmed by the sheer grandeur of these high Sierra marvels, they returned to commune again and again. Artists, photographers, and authors joined the growing procession, and most of them concurred in the opinion that it was “the greatest marvel on the continent.” Increasing appreciation and popularity developed into a movement for segregation under state ownership and operation. In 1864 an application was made for a federal land grant with that end in view. A strong committee, headed by Israel Ward Raymond, drafted the resolution and passed it along to U.S. Senator John Conness. He presented a bill which was passed and signed by President Lincoln on June 29, 1864. The grant was given “upon the express conditions that the premises shall be held for public use, resort and recreation shall be held inalienable for all time.”[270]