Tuesday, April 2, 2019

Tala Point Boulders and Either a Large Erratic or Outcrop

Tala Point is at the north end of a large drumlin ridge that divides entrances to Port Ludlow and Hood Canal. The topographic map indicates boulders at the point.


Indeed, the tip of Tala Point is covered with boulders.

Tala Point. Foulweather Bluff is on the right across the Hood Canal entrance. On the left is Double Bluff on Whidbey Island. The water between Foulwather Bluff and Double Bluff is the entrance to Puget Sound. 

I assumed the boulders at Tala Point were derived from glacial erratics from the eroding glacial drift  of the bluff. However, a closer look shows that this boulders are simply blocks of hard drift.


  
East and south of the point, erosion is much slower and the bluff slope is tree covered and the beach is a broad sandy beach.



However, just off shore is a very large glacial erratic boulder or Is it an isolated bedrock outcrop?  


If this isolated rock is an erratic it is truly immense. It is hard to gauge in the picture above without any scale, but using a GIS tool in an aerial view, the rock is 45 feet long. 

The other possibility is it is an isolated bedrock outcrop. That idea is supported by the geology map of the area combined with the bathymetry on the map.

Geologic Map of the Port Ludlow and Southern Half of the Hansville 7.5-minute Quadrangles, Kitsap and Jefferson Counties, Washington (Polenz, Favia, Hubert, PaulĂ­n, and Cakir, 2015)

The question of erratic versus boulder may or may not be readily solvable. If the rock is not Crescent Formation, then it would be an erratic. However, if it is Crescent it could be an outcrop or an erratic that was not transported very far. 
  


1 comment:

RobertNelson said...

Wow what a great blog, i really enjoyed reading this, good luck in your work. Mapping Services Albany