Redwood Canyon Formation

The Redwood Canyon Formation sits above the Shephard Creek Formation in what’s called a conformable relationship, indicating that the two units represent a continuous span of time. The difference between the two formations is that where the Shephard Creek is fine-grained, the Redwood Canyon Formation is coarse, consisting mostly of wacke (dirty sandstone) and some siltstone. Neither of these rock types is rich in clay, whereas the mudstone and shale of the Shephard Creek Formation are pretty much defined by it.

redwood canyon formation

Again, this unit dates from the Campanian Age of the Late Cretaceous Epoch, which extends from 83 to 71 million years ago. And again, it’s steeply tilted by activity along the nearby Hayward fault, although it was originally laid down in flat-lying beds. It holds up steeper slopes in Shepherd Canyon, being a stronger rock than the underlying unit. Elsewhere, the Redwood Canyon Formation turns into the Pinehurst Shale going upsection, but in Shepherd Canyon that unit does not appear, having been removed by faulting.

There’s another photo from this formation here.

About these ads

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


Follow

Get every new post delivered to your Inbox.

Join 4,096 other followers

%d bloggers like this: