CHATSWORTH, Aug. 19 — Horseback riding in the rugged hills north of here, you can see what has become of the notorious Spahn Movie Ranch, an old, broken-down movie set where Hollywood made a flood of westerns in the 1940s. Long ago, a western scene was created here with a large barn, a couple of shacks, and rows of stables.

Today, there’s a path that leads along a cool, trickling stream, past the ranch’s only remaining ramshackle building. Other trails lead into the hillsides, through groves of oaks with their gnarled roots reaching into dry riverbeds, higher still to the rim of the rocks overlooking the smoggy San Fernando Valley.

A rider can sit below the odd-shaped rocks, listening to the swishing sound of the wind through the waist-high foxtails, and imagine the earth uninhabited. Here you are only 40 miles northwest of downtown Los Angeles, yet, seemingly, you are a world away.

It was such tranquility that attracted Charles Manson to the ranch in 1968 — to put down his roots, to tend to his nomadic flock, to sing of love and talk of hate.

As testimony at Manson’s trial showed, it was from this ranch — almost a year after his arrival — that Manson sent members of his “family” on missions of murder.

Since that time, there has been an unreality to the place, accentuated by the roaring wind and the appearance of total desertion, but even more so by the knowledge of what had begun and ended here.

A run-down movie set, out in the middle of nowhere, from which dark-clad assassins would venture out at night to terrorize and kill, then return before dawn to vanish into its surroundings. It might have been the plot: of a horror film, except that actress Sharon Tate and at least nine other human beings are dead.

It was here in the canyons and gullies behind the ranch and across the road in Devil’s Canyon that the Manson Family hid from police.

Here, too, somewhere in this area, if various accounts are correct, are the remains of Donald “Shorty” Shea, an unemployed stunt cowboy who had lived quietly, peacefully, on the ranch until the Family killed him.

The ranch, where John Wayne and Wallace Berry once borrowed horses for their films, suffered greatly from its notoriety. On a four-day holiday before the murders, for instance, it wasn’t unusual for George Spahn, the blind, 80-ish ranch owner, to take in $1,000 by renting horses at $3 an hour to riders. But following the murders, he didn’t make a cent.

Most of the original Manson followers left the ranch after Manson’s arrest, but a few of his “girls” stayed behind.

But a year later, when Manson was on trial, a brush fire swept through the ranch and destroyed its ramshackle buildings. Three of Manson’s girls, who were at the ranch the day of the fire, left suddenly and never returned.

Some say the fire was nature’s way of purging itself of evil.

Today, one lone foundation is all that remains. Except for Manson, even the ranch’s history has been lost.

Now, it looks as though the pine will get new life. Spahn recently sold his 30 acres to a group of investors who want to build a German-style resort, complete with Bavarian beer gardens, lodges, swimming pools, gift shops, and restaurants.

So far, the investors’ Transcontinental Development Corp. has spent $100,000 grading and landscaping the site for the beer gardens, according to Frank Retz, a director of the firm.

The financiers have run into some problems which have caused delays, however. Sewer construction has stymied the project and it faces new obstacles as Los Angeles County puts together a general development plan that may conflict with the project’s plans.

Retz said it may take two years to settle the issue. Impatient, the investors are undecided whether to go ahead with the tourist center or sell the property.

In the meantime, the old Spahn ranch property sits vacant in the boulder-strewn Santa Susana Mountains.

By JOAN ZYDA