Combine oil, garlic salt, basil, marjoram, thyme and pepper in heavy plastic bag. Mix well. Add roast; coat well with marinade. Marinate in refrigerator 2 hours or overnight.
Line roasting pan with aluminum foil. Combine course kosher salt and the water thoroughly until salt is well moistened. (Do not add more water). Pat 1 cup of moistened salt into a 1/2 inch thick rectangle in pan. Pat roast dry with paper towels. Insert meat thermometer. Place roast on salt layer. Carefully pack remaining salt mixture around meat to encase meat.
Place roast in a 425 degree oven and roast about 16 - 18 minutes per pound for rare (140 degrees), 20 to 22 minutes per pound for medium (160 degrees), or 25-30 minutes per pound for well done (170 degrees). For best results, use a meat thermometer to check internal temperature.
Remove roast when thermometer registers 5 degrees below desired doneness. Let roast stand 5 to 10 minutes in salt crust.
To remove roast from salt, you may need to use a hammer. After removing crust, whisk away any remaining crystals with a stiff pastry or vegetable brush before carving.
If using an instant-read thermometer (the kind that isn't inserted before roasting), check the estimated cooking time. Take roast out of the oven 10-15 minutes bsefore it should be done. You may have to poke a hole in the salt crust to insert themometer. Continue roasting, if needed, and test temperature again in 5 minutes. Enjoy!