WILDFLOWER WALK, Friday

Santa Rosa: Free wildflower walk through meadows at Pepperwood Preserve, 2130 Pepperwood Preserve Road, 10 a.m. - noon. For ages 13 and up, donations accepted. Meet at the Red Barn. Register at pepperwoodpreserve.org

SPRING HIKES, Saturday

Santa Rosa: Naturalist-led spring family hikes at Spring Lake Regional Park, 393 Violetti Road begin at 1, 2 and 3 p.m. from the Discovery Center. Parking $7. Call 707-539-2865 for details.

WILDLIFE EXTRAVAGANZA, Saturday

Glen Ellen: Naturalist John Lynch leads an intermediate, slow-pace 8-mile wildflower hike on back country trails at Jack London State Historic Park, 2400 London Ranch Road, 10 a.m. - 3 p.m. Bring water, binoculars, a camera and wear sturdy shoes. $15 fee includes parking. Register at jacklondonpark.com. Call 707-938-5216 for more information.

TRAIL RAMBLE REGISTRATION, APRIL 20

Calistoga: Registration closes April 20 for the April 23 Napa Trail Ramble between Calistoga and St. Helena at Bothe-Napa State Park, 3801 St. Helena Highway North. Choose between a 10K or 10-mile run. Hikers also welcome. Registration is $65 for the 10K and $75 for the 10-miler at ultrasignup.com. Post-race barbecue with beer and wine. Proceeds benefit the Leave Your Mark scholarship at Pacific Union College. More information is available at healdsburgrunningcompany.com.

SONOMA GEOLOGY, APRIL 20

Santa Rosa: Dr. Jane Nielsen discusses the unique geology of the Laguna de Santa Rosa Watershed and the location of earthquake fault, 7-8:30 p.m. at Heron Hall at the Laguna Environmental Center, 900 Sanford Road. $10. Tea and light snacks provided. Register at lagunafoundation.org.