I bet you have never seen Black Birch trees this small. The cotyledons are well deployed but the true leaves have yet to come out.
I am always astonished by the strength of these small sprouts capable of lifting heavy pieces of dirt or wood to reach out for the sun.
This last picture reminds me of the United States victory at the Battle of Iwo Jima during World War II. Together the small Birches unite their forces and lift a massive piece of wood.