CA Plein Air Landscape painting

Fine California Plein Air painting picked up at a local Estate Sale yesterday, but had no signature. Painting shows a little wear, but no tears or holes (just a VERY slight "dent" that is hard to see unless you look at the canvas up close). Painting is old for it shows years of grime on the surface, as well as the back canvas (a bit of yellowing), perhaps by cig smoke in years past? Style shows true "Plein Air" as to the brush strokes which may indicate it was done on site and out of doors, very free hand that shows some skill (in my opinion) and well balanced comp. and colors, great light and shadows. Similar to the artists I like such as Anna Hills and William Wendt. May have been painted in So. Ca based on having Eucalyptus trees, and mountian ranges similar to other paintings I have seen of So. CA where I grew up. Fame looks period, perhaps origional to the picture with some damage and repair. Hard for me to date, but thinking late teens or 20s, but possibly later? Seller had not information on the painting.