Sandy spits, mud flats, and sandy beaches return which pair of echoes?

• A. Brightest and Strongest
• B. Poorest and Weakest
• C. Faintest and Narrowest
• D. Largest and Distinct

Answer: (B)

Soft bottoms like sandy spits, mud flats, and sandy beaches absorb much of the sonar energy and reflect only a small portion back to the transducer. The acoustic impedance difference between water and these sediments is small, so the echo is weak and faint. That’s why the echoes from these surfaces are described as the poorest and weakest. In contrast, hard bottoms (rocky or firm) reflect more energy, giving brighter, stronger echoes, which wouldn’t fit soft sediments.