TERTIARY FORMATION. 655 
first to be an instance of granite intersecting tertiary shale; but a far- 
ther examination proved it to be identical with the granitic sandstone 
of the opposite shores of the Columbia. Large fragmentsand chips 
of the adjoining argillaceous beds are imbedded in the sandstone of 
the dike. Twenty feet up the face of the bluff there is a fault of eight 
Fig. 1. Fig. 2. 
feet, (figure 1,) and below, near the bottom, there is another lateral slide 
of less extent. 
Towards Tongue Point, two and a half miles above Astoria, there 
are several of these pseudo-dikes; and they are generally faulted. 
One of them is represented in figure 2; the width is eighteen inches, 
and the course east-by-south. It has been faulted obliquely six feet 
above the foot of the cliff; the upper part was carried to the left, and 
fell three feet below its former position. The concussion at the time of 
the fracture almost obliterated the lower extremity of the upper part. 
Near this place, there is another small pseudo-dike, six inches wide, 
running east and west. Fifty yards farther to the eastward, there are 
two dikes, the left of which is six inches wide near the top of the cliff, 
and eight inches below; the one to the right is five inches wide. 
The fault which they have experienced is oblique and irregular. 
On the opposite shores of the Columbia, at the west cape of Gray’s 
a“ 
