The material mass of the city — the roads, the bridges, the buildings — must come from somewhere. For Los Angeles, that somewhere has often been Irwindale. Over millions of years, the San Gabriel Mountains and their largest river deposited a massive pile of rocks and gravel ideally suited for construction underneath the inland city. And so, as Los Angeles has risen upward and outward, Irwindale has sunk downward. On this flat, 20-mile, morning bicycle tour, we will peer down into the City of Irwindale’s finest craters and visit some former pits that have been (mostly) filled and transformed.

Meet at the Irwindale Gold Line Station. The ride will start at 9am.

Please note:

• The Metro Gold Line takes about 45 minutes to get to Irwindale Station from Union Station. Please arrive early.

• This is a slow-paced ride suitable for casual and occasional riders. No one will be turned away or left behind.

• The ride is almost entirely flat, with only a few man-made inclines that are short and very walkable, if necessary.

• There are several stretches that are unpaved. They are all reasonably easy but, if you have the option, we recommended a wider-tired bicycle.

• Please bring a functioning bike and at least two bottles of water, sunscreen, and whatever else you may need for a warm, summer morning in the sun.

• The ride will end around noon at the Duarte/City of Hope Gold Line Station. If you drive to the start, you can easily ride the train one stop back to your vehicle.