Montana de Oro Strike and Dip Trip

Off campus field-lab | Back to the GEOL 241 Homepage



In this field-lab we will learn how to use a Brunton compass to measure the orientation of tilted mudstone (although it's commonly referred to as shale) beds along the coastline at Montana de Oro State Park. These rocks are part of the Monterey Formation. You will plot this orientation data onto a profile and construct a simple cross-section to identify a geologic structure.

The purpose of this activity is to yet again think in three-dimensions, and to think about how a cross-section can guide you into determining the geologic history that led to the structure seen today.

Preparation & Review

Please look at 9.3.2, 9.4.1, and 9.4.2 in this book: An Introduction to Geology – Free Textbook for College-Level Introductory Geology Courses (, or any corresponding sections of a physical geology book you already have.


Handouts will be provided at the trip, but copies are available below:

Field Activity

Field handout

Post field-lab assignment

Turn in the cross-section/block-diagram activity at our next meeting.


I will bring the Brunton compasses.

What to bring:

The measurement sights are along the sandy beaches and the terrain to get to the sights is flat trail (Bluff Trail at Montana de Oro) - much easier than our Poly Canyon adventures.

Meeting Location

We will meet in Lot H-12 on campus at 8:00 a.m. and caravan our cars to Montana de Oro.


From Cal Poly to Montana de Oro State Park: map and directions.

Park in the main parking lot in front of the white state park office/house on the bluff overlooking Spooner's Cove.