Saturday, December 1, 2018

Lake Ontario has been in a constant state of change since the end of the last ice age.  When the ice was melting about 12,000 years ago the lake was much larger than it is today.  That lake had a shoreline that was farther inland that today’s.  The larger lake has been named Lake Iroquois.  The Scarborough Bluffs are part of the old shoreline as is the rise in land on Spadina near Casa Loma.  At the west end of the lake, the old shoreline is visible in places like Iroquois Shoreline Woods Park in Oakville.  There is a small parking lot and forest access on Joshua Creek Drive but it is gated at this time of the year.  There are also several places where you can park on the street and access the park, including Edgeware Road.

The old Iroquois shoreline is one of the major geological land forms in the GTA.  When Lake Iroquois covered the lower part of the park, the lake was at the largest it has been in recent history.  Suddenly, the lake drained away through the Hudson River leaving a much smaller lake known as Lake Admiralty.  This lake sat in the basin of modern Lake Ontario.  Over time the lake has slowly been filling back up so that it has reached the shoreline we know today.  Iroquois Shoreline Woods Park was one of the last large undisturbed Carolinian forests in the area.  Carolinian forests are climax forests and consist of red oak, white oak, various maple, hickory and beech trees.  The picture below shows the rise in land that marks the old shoreline.

Several staircases provide access to the park and these all seem to be in a good state of repair.  The park had been shut down due to the condition of the forest but efforts to restore it have been successful and there are five sites where significant new plantings have taken place.

Joshua Creek sometimes forms the border between Oakville and Mississauga and has headwaters just north of the 407.  The forest around the creek has been thinned out considerably by the removal of ash trees to deal with the problem of emerald ash borers which have killed almost all ash trees in the GTA.  Controlled burns in the park have also left a scattering of burnt tree stumps.  All the stumps and downed trees have been left because they form part of the ecosystem in the forest.

Witches’ Butter is a golden jelly type of mushroom that can grow all year.  It appears on warmer days in the middle of winter but in the summer is found in cool places, usually at higher elevations.  It is considered edible and is sometimes added to soups but in my opinion it looks better on the stump than it would on my plate.

Along the way we noticed the family in one house has added indoor rock climbing hand and foot holds on the back of their shed.

Sheridan Valley Park connects the upper and lower sections of Iroquois Shoreline Woods Park and contains this extensive stairway that allows access to the park from the subdivision.

Puffball mushrooms are named for the way in which they spread their spores.  These purple spored puffballs have developed a small hole on the top where the spores are released when the ball is hit by heavy rain drops.

The short video below shows the spores being released from the opening on the top of each puffball.  Hitting the balls with a small stick created a cloud of spores which may serve to start another small colony of puffballs next year.

Iroquois Shoreline Woods Park is large enough, and has plenty of trails, making it an ideal place to visit multiple times.

Google Maps Link: Iroquois Shoreline Woods Park

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