Well... this is probably going to be harder than drawing the cct...
With the switch open, the LED won't operate. Also, c2 & c1 are discharged. So, u1a out is high, u1b out is low, u1c out is high. u1f out is low due to high through d6. Both oscillators are disabled by the high levels through diodes to their inputs.
When the switch closes, the led conducts. after 1 minute, c2 charges enough to flip u1a output to low. So d4 & d6 no longer conduct. u1e is now able to oscillate @ 1Hz, which pulses the LED at this frequency.
After 1 more minute, c1 is charged enough to flip u1b output high. u1e osc is disabled through d5. u1c output goes low, u1d osc is enable as d3 no longer conducts. u1d osc pulses led @ 4Hz. From now on nothing new happens, so 4Hz pulse continues.
When switch is opened again (LED off - C2 may discharge through it), C2 discharges through d1 & r3, then c2 discharges through d2, now everythings back to the original state.
Simple, what? There's enough diodes to make a small uC!