Naturalist Segment: Wilder Marine Terraces
April 29, 2019
Up next in our Science Committee's Naturalist Segment is this fascinating insight about marine terraces written by SeanPaul Laselle. Consider this: when you ride the Old Cabin Classic race course in Wilder Ranch State Park, for every vertical foot you climb, you are traveling back in time 700 hundred years! Keep reading to learn more!
Words by SeanPaul Laselle
The Old Cabin Classic course starts riders off enjoying the cool ocean breeze along the Ohlone Bluff Trail before making everyone sweat it up the steep, stairstep-like hills along Baldwin and Engelsmans Loops. We can both curse and thank gradual tectonic uplift which combined forces with sea level rise and fall over hundreds of thousands of years to create the marine terraces that dominate the topography of Wilder Ranch. As sea level rises, ocean waves erode a broad terrace and cut into the shoreline (modern examples can be seen along the Ohlone Bluff Trail). As sea level falls, these platforms and sea cliffs are if they are uplifted high enough before sea level rises again.
Photo by Andy Bokanev
The youngest marine terrace, which underlies Hwy 1, most of the coastal agricultural fields, and the lower Westside, is about 125,000 years old. The first steep climb of the race takes you up an ancient sea cliff to the Western Terrace, about 210,000 years old. The high point of the course turns you back downhill on the Wilder Terrace, 320,000 years old. Therefore, for every vertical foot you climb during the race, you are traveling back in time 700 hundred years! It may not feel like you’re going fast when suffering up these hills, but the rocks think you’re crushing it!
Photo by Mike Thomas
SeanPaul LaSelle's love for science and cycling goes back to the days of trying to eat rocks on hikes and sitting in the baby seat on his dad's bike in Washington state. Now in Santa Cruz, as a sedimentologist, a member of the MBOSC science committee, and trail crew leader in training, SeanPaul is excited to help MBOSC in its mission to practice and promote sustainable mountain biking.
Words by SeanPaul Laselle
The Old Cabin Classic course starts riders off enjoying the cool ocean breeze along the Ohlone Bluff Trail before making everyone sweat it up the steep, stairstep-like hills along Baldwin and Engelsmans Loops. We can both curse and thank gradual tectonic uplift which combined forces with sea level rise and fall over hundreds of thousands of years to create the marine terraces that dominate the topography of Wilder Ranch. As sea level rises, ocean waves erode a broad terrace and cut into the shoreline (modern examples can be seen along the Ohlone Bluff Trail). As sea level falls, these platforms and sea cliffs are if they are uplifted high enough before sea level rises again.
Photo by Andy Bokanev
The youngest marine terrace, which underlies Hwy 1, most of the coastal agricultural fields, and the lower Westside, is about 125,000 years old. The first steep climb of the race takes you up an ancient sea cliff to the Western Terrace, about 210,000 years old. The high point of the course turns you back downhill on the Wilder Terrace, 320,000 years old. Therefore, for every vertical foot you climb during the race, you are traveling back in time 700 hundred years! It may not feel like you’re going fast when suffering up these hills, but the rocks think you’re crushing it!
Photo by Mike Thomas
Heights and Ages of Marine Terraces
Ages and heights are from Weber and Allwardt, 2001:- 1st terrace: Santa Cruz terrace is currently 50 ft asl, 105,000 years old.
- 2nd terrace: Western Terrace currently 300 ft asl, 213,000 years old.
- The first hard climb is 250 ft and ~90,000 years. So every foot you go up is 360 years of time.
- 3rd terrace: Wilder Terrace is currently 460 ft asl, 320,000 years old.
- From the start at bottom of Engelsman (Santa Cruz terrace) to Twin Gates (Wilder Terrace), is a 410 ft climb over is about 700 years per foot.
SeanPaul LaSelle's love for science and cycling goes back to the days of trying to eat rocks on hikes and sitting in the baby seat on his dad's bike in Washington state. Now in Santa Cruz, as a sedimentologist, a member of the MBOSC science committee, and trail crew leader in training, SeanPaul is excited to help MBOSC in its mission to practice and promote sustainable mountain biking.
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